Tumor necrosis factor receptor superfamily members 1a and 1b contribute to exacerbation of atherosclerosis by Chlamydia pneumoniae in mice.

The host immune responses that mediate Chlamydia-induced chronic disease sequelae are incompletely understood. The role of TNF-α, TNF receptor 1 (TNFR1), and TNF receptor 2 (TNFR2), in Chlamydia pneumoniae (CPN)-induced atherosclerosis was studied using the high-fat diet-fed male C57BL/6J mouse model. Following intranasal CPN infection, TNF-α knockout (KO), TNFR1 KO, TNFR2 KO, and TNFR 1/2 double-knockout, displayed comparable serum anti-chlamydial antibody response, splenic antigen-specific cytokine response, and serum cholesterol profiles compared to wild type (WT) animals. However, atherosclerotic pathology in each CPN-infected KO mouse group was reduced significantly compared to WT mice, suggesting that both TNFR1 and TNFR2 promote CPN-induced atherosclerosis.

Intranasal immunization with recombinant chlamydial protease-like activity factor attenuates atherosclerotic pathology following Chlamydia pneumoniae infection in mice.

We have shown previously that intranasal vaccination with recombinant chlamydial protease-like activity factor (rCPAF: antigen) and interleukin-12 (IL-12) as an adjuvant induces robust protection against pathological consequences of female genital tract infection with Chlamydia muridarum, a closely related species and a rodent model for the human pathogen Chlamydia trachomatis. Another related species Chlamydia pneumoniae, a human respiratory pathogen, has been associated with exacerbation of atherosclerotic pathology. CPAF is highly conserved among Chlamydia spp. leading us to hypothesize that immunization with rCPAF with IL-12 will protect against high-fat diet (HFD) and C. pneumoniae-induced acceleration of atherosclerosis. rCPAF ± IL-12 immunization induced robust splenic antigen (Ag)-specific IFN-γ and TNF-α production and significantly elevated serum total anti-CPAF Ab, IgG2c, and IgG1 antibody levels compared to mock or IL-12 alone groups. The addition of IL-12 to rCPAF significantly elevated splenic Ag-specific IFN-γ production and IgG2c/IgG1 anti-CPAF antibody ratio. Following intranasal C. pneumoniae challenge and HFD feeding, rCPAF ± IL-12-immunized mice displayed significantly enhanced splenic IFN-γ, not TNF-α, response on days 6 and 9 after challenge, and significantly reduced lung chlamydial burden on day 9 post-challenge compared to mock- or IL-12-immunized mice. Importantly, rCPAF ± IL-12-immunized mice displayed significantly reduced atherosclerotic pathology in the aortas after C. pneumoniae challenge. Serum cholesterol levels were comparable between the groups suggesting that the observed differences in pathology were due to protective immunity against the infection. Together, these results confirm and extend our previous observations that CPAF is a promising candidate antigen for a multisubunit vaccine regimen to protect against Chlamydia-induced pathologies, including atherosclerosis.

Empathy and Osteopathic Manipulative Medicine: Is It All in the Hands?

CONTEXT: The osteopathic medical school curriculum is unique because of the inclusion of training in osteopathic manipulative medicine (OMM). Interest in and use of OMM promotes cognitive training in diagnosing conditions, emotional training in the alleviation of pain, and physical training in the application of OMM. Osteopathic manipulative medicine may mitigate a reduction in empathy levels of medical students and explain why osteopathic medical students do not follow the declining pattern of empathy previously reported in allopathic medical students. OBJECTIVE: To examine whether favorable opinions of OMM are positively correlated with overall student empathy as well as the cognitive, emotional, and behavioral subcomponents of empathy. METHODS: Institutional review board approval was obtained to measure empathy in medical students attending the Midwestern University/Chicago College of Osteopathic Medicine for this cross-sectional study. The 20-item Jefferson Scale of Empathy medical student version (JSE-S) was distributed via email to first-year students at the beginning of the 2016-2017 academic year and at the end of the academic year to all students. Items were divided into cognitive, emotional, and behavioral categories. Items related to demographics, interest and use of OMM and the osteopathic philosophy, frequency of touch, and personality were also included in the survey. Data were analyzed using SPSS software and presented as mean (SEM). Statistical significance was set at P<.05. RESULTS: Of the 801 students the survey was sent to at the end of the 2016-2017 academic year, 598 students completed the survey, for a response rate of 75%. When accounting for the effect of gender with a multivariate analysis of covariance, there were no differences in empathy scores across school years. When empathy scores from first- and second-year students were combined and compared with combined third- and fourth-year students' scores to examine the difference between empathy in students during academic and clinical training, a difference in the mean (SEM) JSE-S empathy score was noted (114.6 [0.7] and 112.0 [0.7], respectively; P=.01); however, the effect size was small (partial η2=0.01). Interest in OMM and the osteopathic philosophy were significantly associated with higher empathy scores (P<.05; medium effect; partial η2=0.08). CONCLUSION: Interest in and use of OMM are associated with higher empathy scores and empathy subcomponents. Training and use of OMM should be examined as a mechanism contributing to the durability of empathy in the osteopathic medical profession.

Does Osteopathic Manipulative Treatment Make a Neuropsychological Difference in Adults With Pain? A Rationale for a New Approach.

Cognitive impairment is common in patients with pain. While symptoms of pain are effectively treated with osteopathic manipulative treatment (OMT), the cognitive complaint is vastly ignored. Pain-induced cognitive dysfunction can be severe and is particularly apparent in working memory and attention. There is good reason to expect cognitive responsiveness to OMT. Previous research has reported the effects of OMT on related psychiatric outcomes, including relief from depression and anxiety, suggesting that OMT may produce more cortical benefits than is currently thought. The rationale to link OMT to cognition comes from the tenets of osteopathic medicine: body unity, homeostasis, and the structure-function relationship. The present article provides background evidence to support the hypothetical link between OMT and cognitive benefits and proposes a physiological mechanism of how OMT could exert its effect on cognition. Research strategies are discussed to test the hypotheses that are generated from the proposed theoretical framework.

Cognitive, Behavioral and Emotional Empathy in Pharmacy Students: Targeting Programs for Curriculum Modification.

INTRODUCTION: Empathy is an essential trait for pharmacists and is recognized as a core competency that can be developed in the classroom. There is a growing body of data regarding levels of empathy in pharmacy students; however, these studies have not measured differences in behavioral, cognitive, and emotional empathy. The goal of this study was to parse the underlying components of empathy and correlate them to psychosocial attributes, with the overall goal of identifying curriculum modifications to enhance levels of empathy in pharmacy students. METHODS: IRB approval was obtained to measure empathy levels in pharmacy students attending Midwestern University. An online, anonymous survey administered through a secure website (REDCap) was used. This survey utilized the Jefferson Scale of Empathy (Medical Student version) and included questions regarding demographics and personality traits. Empathy questions were sub-divided into behavioral, cognitive, and emotional categories. Data are presented as mean ± SEM with significance set at P ≤ 0.05. RESULTS: Three hundred and four pharmacy students at Midwestern University participated in a fall survey with an overall response rate of 37%. The average empathy score was 110.4 ± 0.8 on a scale of 20-140; which is comparable to empathy scores found by Fjortoft et al. (2011) and Van Winkle et al. (2012b). Validating prior research, females scored significantly higher than males in empathy as well as behavioral, cognitive, and emotional subcomponents. For the entire population, emotional empathy was significantly higher than cognitive and behavioral empathy (P < 0.05). Furthermore, negative correlations to empathy were observed for self-serving behavior (R D 0.490, P < 0.001), medical authoritarianism (R D 0.428, P < 0.001), and experience of coercion (R D 0.344, P < 0.001). CONCLUSION: Overall, empathy levels in pharmacy students are similar to prior studies with females scoring higher than males. Emotional empathy may play a greater role than cognitive and behavioral empathy in this group of students. Targeted programs that promote volunteerism and activities that foster responsiveness to patient needs may attenuate self-serving behavior and medical authoritarianism and, therefore, improve empathy levels in pharmacy students.

CD8+ T cells mediate Chlamydia pneumoniae-induced atherosclerosis in mice.

Chlamydia pneumoniae is a community-acquired bacterial pathogen that has been strongly associated with exacerbation of atherosclerosis. We evaluated the role of CD8(+) T cells in the C57BL/6J mouse model of C. pneumoniae-induced atherosclerosis. Groups of 4- to 6-week-old male wild-type C57BL/6J (WT) mice and mice with a gene deficiency in CD8α (CD8 KO mice) were infected with C. pneumoniae and fed a high fat (HF) diet. Serum antibody response and serum cholesterol were comparable between infected CD8 KO and WT mice. However, infected CD8 KO mice displayed significantly reduced atherosclerotic plaque lesions on day 100 compared to infected WT mice, at a level comparable to both uninfected WT and CD8 KO mice fed the HF diet. Moreover, repletion of CD8 KO mice with WT CD8(+) T cells (1 × 10(7) cells/mouse intravenously) at the time of infection reverted atherosclerotic plaque lesions to WT levels. These results demonstrate that CD8(+) T cells play an important role in mediating C. pneumoniae-induced exacerbation of atherosclerotic pathology.

Mountaineering-induced bilateral plantar paresthesia.

CONTEXT: Flat feet (pes planus) have been implicated in multiple musculoskeletal complaints, which are often exacerbated by lack of appropriate arch support or intense exercise. OBJECTIVE: To investigate the efficacy of osteopathic manipulative treatment (OMT) on a patient (K.K.H.) with mountaineering-induced bilateral plantar paresthesia and to assess the association of pes planus with paresthesia in members of the mountaineering expedition party that accompanied the patient. METHODS: A patient history and physical examination of the musculoskeletal system were performed. The hindfoot, midfoot, forefoot, big toe, and distal toes were evaluated for neurologic function, specifically pin, vibration, 10-g weight sensitivity, and 2-point discrimination during the 4-month treatment period. To determine if OMT could augment recovery, the patient volunteered to use the contralateral leg as a control, with no OMT performed on the sacrum or lower back. To determine if pes planus was associated with mountaineering-induced paresthesia, a sit-to-stand navicular drop test was performed on members of the expedition party. RESULTS: Osteopathic manipulative treatment improved fibular head motion and muscular flexibility and released fascial restrictions of the soleus, hamstring, popliteus, and gastrocnemius. The patient's perception of stiffness, pain, and overall well-being improved with OMT. However, OMT did not shorten the duration of paresthesia. Of the 9 expedition members, 2 experienced paresthesia. Average navicular drop on standing was 5.1 mm for participants with no paresthesia vs 8.9 mm for participants with paresthesia (t test, P<.01; Mann-Whitney rank sum test, P=.06). CONCLUSION: These preliminary findings suggest that weakened arches may contribute to mountaineering-induced plantar paresthesia. Early diagnosis of pes planus and treatment with orthotics (which may prevent neuropathies)--or, less ideally, OMT after extreme exercise--should be sought to relieve tension and discomfort.

Cardiac myosin binding protein-C is a potential diagnostic biomarker for myocardial infarction.

Cardiac myosin binding protein-C (cMyBP-C) is a thick filament assembly protein that stabilizes sarcomeric structure and regulates cardiac function; however, the profile of cMyBP-C degradation after myocardial infarction (MI) is unknown. We hypothesized that cMyBP-C is sensitive to proteolysis and is specifically increased in the bloodstream post-MI in rats and humans. Under these circumstances, elevated levels of degraded cMyBP-C could be used as a diagnostic tool to confirm MI. To test this hypothesis, we first established that cMyBP-C dephosphorylation is directly associated with increased degradation of this myofilament protein, leading to its release in vitro. Using neonatal rat ventricular cardiomyocytes in vitro, we were able to correlate the induction of hypoxic stress with increased cMyBP-C dephosphorylation, degradation, and the specific release of N'-fragments. Next, to define the proteolytic pattern of cMyBP-C post-MI, the left anterior descending coronary artery was ligated in adult male rats. Degradation of cMyBP-C was confirmed by a reduction in total cMyBP-C and the presence of degradation products in the infarct tissue. Phosphorylation levels of cMyBP-C were greatly reduced in ischemic areas of the MI heart compared to non-ischemic regions and sham control hearts. Post-MI plasma samples from these rats, as well as humans, were assayed for cMyBP-C and its fragments by sandwich ELISA and immunoprecipitation analyses. Results showed significantly elevated levels of cMyBP-C in the plasma of all post-MI samples. Overall, this study suggests that cMyBP-C is an easily releasable myofilament protein that is dephosphorylated, degraded and released into the circulation post-MI. The presence of elevated levels of cMyBP-C in the blood provides a promising novel biomarker able to accurately rule in MI, thus aiding in the further assessment of ischemic heart disease.

Novel approach to admittance to volume conversion for ventricular volume measurement.

The conductance catheter is a widely used tool to determine ventricular volumes in animal models. A tetra-polar catheter is inserted into the ventricle to measure instantaneous conductance, which is a combination of ventricular blood and surrounding myocardium. Various techniques have been used to separate the blood conductance signal from the combined measured signal [1], [2]. The blood conductance is then converted to volume using a linear relationship proposed by Baan [1] or an improved non linear relationship proposed by Wei [3]. We propose a novel approach that uses the combined blood-muscle signal to calculate volume, thereby eliminating the need to subtract out the muscle. In vivo experiments were performed in mice to validate this new approach and the results were compared with volumes obtained using ultrasound imaging.

Role of FRNK tyrosine phosphorylation in vascular smooth muscle spreading and migration.

AIMS: Focal adhesion kinase (FAK) and its autonomously expressed, C-terminal inhibitor FAK-related non-kinase (FRNK), are important regulators of vascular smooth muscle cell (VSMC) spreading and migration. However, the mechanisms of FRNK-mediated inhibition of FAK-dependent signalling are not fully defined. The aim of this study was to determine the potential role of FRNK tyrosine phosphorylation in regulating these processes. METHODS AND RESULTS: Rat carotid arteries were balloon-injured and FAK and FRNK expression and phosphorylation were examined by immunocytochemistry, immunoprecipitation, and western blotting with total and phosphospecific antibodies. FAK and FRNK expression increased four- and nine-fold, respectively, in alpha-smooth muscle actin-positive VSMCs of injured arteries when compared with contralateral control arteries, and the upregulated FRNK was phosphorylated at residues Y168 and Y232. In A7r5 cells (an embryonic rat VSMC line), endogenously expressed FRNK was also phosphorylated at Y168 and Y232 under basal conditions, and Y168/Y232 phosphorylation increased in response to angiotensin II treatment. When overexpressed in A7r5 cells and adult rat aortic smooth muscle cells (RASM), wild-type (wt) GFP-tagged FRNK was also phosphorylated at residues Y168 and Y232, and GFP-wtFRNK inhibited cell spreading and migration. Mutation of GFP-FRNK at Y168 (GFP-Y168F-FRNK) abrogated FRNK-mediated inhibition of cell spreading and migration, but did not affect its localization in VSMC focal adhesions or its ability to inhibit FAK tyrosine phosphorylation. CONCLUSION: Phosphorylation of Y168 on FRNK may represent a novel mechanism by which FRNK inhibits cell spreading and migration in VSMCs.

Physiological replacement of T3 improves left ventricular function in an animal model of myocardial infarction-induced congestive heart failure.

BACKGROUND: Patients with congestive heart failure (CHF) often have low serum triiodothyronine (T(3)) concentrations. In a rodent model of myocardial infarction-induced CHF and low serum T(3), we hypothesized that replacing T(3) to euthyroid levels would improve left ventricular function without producing untoward signs of thyrotoxicosis. METHODS AND RESULTS: Adult male Sprague-Dawley rats were subjected to left anterior descending coronary artery ligation (myocardial infarction). One week post-myocardial infarction, left ventricular fractional shortening was significantly reduced to 22+/-1% in CHF animals versus 38+/-1% for sham-operated controls (P<0.001). Serum T(3) concentration was also significantly reduced (80+/-3 versus 103+/-6 ng/dL; P<0.001), in CHF animals versus Shams. At 9 weeks post-myocardial infarction, systolic function (+dP/dt max) was significantly attenuated in CHF animals (4773+/-259 versus 6310+/-267 mmHg/s; P<0.001) as well as diastolic function measured by half time to relaxation (15.9+/-1.2 versus 11.1+/-0.3 ms; P<0.001). alpha-myosin heavy chain expression was also significantly reduced by 77% (P<0.001), and beta-myosin heavy chain expression was increased by 21%. Continuous T(3) replacement was initiated 1 week post-myocardial infarction with osmotic mini-pumps (6 microg/kg/d), which returned serum T(3) concentrations to levels similar to Sham controls while resting conscious heart rate, arterial blood pressure and the incidence of arrhythmias were not different. At 9 weeks, systolic function was significantly improved by T(3) replacement (6279+/-347 mmHg/s; P<0.05) and a trend toward improved diastolic function (12.3+/-0.6 ms) was noted. T(3) replacement in CHF animals also significantly increased alpha- and reduced beta-MHC expression, (P<0.05). CONCLUSIONS: These data indicate that T(3) replacement to euthyroid levels improves systolic function and tends to improve diastolic function, potentially through changes in myocardial gene expression.

CRNK gene transfer improves function and reverses the myosin heavy chain isoenzyme switch during post-myocardial infarction left ventricular remodeling.

PYK2 is a Ca(2+)-dependent, nonreceptor protein tyrosine kinase that is involved in the induction of left ventricular hypertrophy (LVH) and its transition to heart failure. We and others have previously investigated PYK2's function in vitro using cultured neonatal and adult rat ventricular myocytes as model systems. However, the function of PYK2 in the in vivo adult heart remains unclear. Here we evaluate the effect of PYK2 inhibition following myocardial infarction (MI) using adenoviral (Adv) overexpression of the C-terminal domain of PYK2, known as CRNK. First we demonstrate that CRNK functions as a dominant-negative inhibitor of PYK2-dependent signaling, presumably by displacing PYK2 from focal adhesions and costameres. Then, male Sprague-Dawley rats (~300 g) underwent permanent left anterior descending coronary artery ligation. One wk post-MI, either Adv-GFP (n=34) or Adv-CRNK (n=28) was administered (10(10) pfu, 0.1 ml) via catheter-based, Optison-mediated gene transfer. LV structure and function were evaluated by echocardiography 1 and 3 wk after gene transfer, and LV tissue was analyzed by real-time RT-PCR and Western blotting. CRNK overexpression was readily detected by Western blotting 1 wk following gene transfer. Adv-CRNK improved overall survival (P=0.03; Logrank Test) and LV fractional shortening (23+/-2% vs. 31+/-2% for Adv-GFP vs. Adv-CRNK infected animals, respectively; P<0.05). Whereas MI hearts exhibited increased beta-, and decreased alpha-myosin heavy chain (MHC) mRNA expression characteristic of LVH, Adv-CRNK reversed the MHC isoenzyme switch (3.3+/-1.4 fold increase in alpha MHC; 0.4+/-0.1 fold decrease in beta MHC; P<0.05 for both). In summary, CRNK gene transfer improves survival, increases LV function, and alters MHC gene expression suggesting an attenuation of LV remodeling post-MI.

Vascular KCNQ potassium channels as novel targets for the control of mesenteric artery constriction by vasopressin, based on studies in single cells, pressurized arteries, and in vivo measurements of mesenteric vascular resistance.

Pressor effects of the vasoconstrictor hormone arginine vasopressin (AVP), observed when systemic AVP concentrations are less than 100 pM, are important for the physiological maintenance of blood pressure, and they are also the basis for therapeutic use of vasopressin to restore blood pressure in hypotensive patients. However, the mechanisms by which circulating AVP induces arterial constriction are unclear. We examined the novel hypothesis that KCNQ potassium channels mediate the physiological vasoconstrictor actions of AVP. Reverse transcriptase polymerase chain reaction revealed expression of KCNQ1, KCNQ4, and KCNQ5 in rat mesenteric artery smooth muscle cells (MASMCs). Whole-cell perforated patch recordings of voltage-sensitive K+ (Kv) currents in freshly isolated MASMCs revealed 1,3-dihydro-1-phenyl-3,3-bis(4-pyridinylmethyl)-2H-indol-2-one (linopirdine)- and 10,10-bis(4-pyridinylmethyl)-9(10H)-anthracenone (XE-991)-sensitive KCNQ currents that were electrophysiologically and pharmacologically distinct from other Kv currents. Suppression of KCNQ currents by AVP (100 pM) was associated with significant membrane depolarization, and it was abolished by the protein kinase C (PKC) inhibitor calphostin C (250 nM). The KCNQ channel blocker linopirdine (10 microM) inhibited KCNQ currents in MASMCs, and it induced constriction of isolated rat mesenteric arteries. The vasoconstrictor responses were not additive when combined with 30 pM AVP, and they were prevented by the L-type Ca2+ channel blocker verapamil. Ethyl-N-[2-amino-6-(4-fluorophenylmethylamino)pyridin-3-yl] carbamic acid (flupirtine) significantly enhanced KCNQ currents, and it reversed constrictor responses to 30 pM AVP. In vivo, i.v. administration of linopirdine induced a dose-dependent increase in mesenteric artery resistance and blood pressure, whereas flupirtine had the opposite effects. We conclude that physiological concentrations of AVP induce mesenteric artery constriction via PKC-dependent suppression of KCNQ currents and L-type Ca2+ channel activation in MASMCs.

Vasopressin-induced vasoconstriction: two concentration-dependent signaling pathways.

Current scientific literature generally attributes the vasoconstrictor effects of [Arg(8)]vasopressin (AVP) to the activation of phospholipase C (PLC) and consequent release of Ca(2+) from the sarcoplasmic reticulum. However, half-maximal activation of PLC requires nanomolar concentrations of AVP, whereas vasoconstriction occurs when circulating concentrations of AVP are orders of magnitude lower. Using cultured vascular smooth muscle cells, we previously identified a novel Ca(2+) signaling pathway activated by 10-100 pM AVP. This pathway is distinguished from the PLC pathway by its dependence on protein kinase C (PKC) and L-type voltage-sensitive Ca(2+) channels (VSCC). In the present study, we used isolated, pressurized rat mesenteric arteries to examine the contributions of these different Ca(2+) signaling mechanisms to AVP-induced vasoconstriction. AVP (10(-14)-10(-6) M) induced a concentration-dependent constriction of arteries that was reversible with a V(1a) vasopressin receptor antagonist. Half-maximal vasoconstriction at 30 pM AVP was prevented by blockade of VSCC with verapamil (10 microM) or by PKC inhibition with calphostin-C (250 nM) or Ro-31-8220 (1 microM). In contrast, acute vasoconstriction induced by 10 nM AVP (maximal) was insensitive to blockade of VSCC or PKC inhibition. However, after 30 min, the remaining vasoconstriction induced by 10 nM AVP was partially dependent on PKC activation and almost fully dependent on VSCC. These results suggest that different Ca(2+) signaling mechanisms contribute to AVP-induced vasoconstriction over different ranges of AVP concentration. Vasoconstrictor actions of AVP, at concentrations of AVP found within the systemic circulation, utilize a Ca(2+) signaling pathway that is dependent on PKC activation and can be inhibited by Ca(2+) channel blockers.

Pharmacological and electrophysiological characterization of store-operated currents and capacitative Ca(2+) entry in vascular smooth muscle cells.

Capacitative Ca(2+) entry (CCE) in vascular smooth muscle cells contributes to vasoconstrictor and mitogenic effects of vasoactive hormones. In A7r5 rat aortic smooth muscle cells, measurements of cytosolic free Ca(2+) concentration ([Ca(2+)](i)) have demonstrated that depletion of intracellular Ca(2+) stores activates CCE. However, there is disagreement in published studies regarding the regulation of this mechanism by the vasoconstrictor hormone [Arg(8)]-vasopressin (AVP). We have employed electrophysiological methods to characterize the membrane currents activated by store depletion [store-operated current (I(SOC))]. Because of different recording conditions, it has not been previously determined whether I(SOC) corresponds to CCE measured using fura-2; nor has the channel protein responsible for CCE been identified. In the present study, the pharmacological characteristics of I(SOC), including its sensitivity to blockade by 2-aminoethoxydiphenylborane, diethylstilbestrol, or micromolar Gd(3+), were found to parallel the effects of these drugs on thapsigargin- or AVP-activated CCE measured under identical external ionic conditions using fura-2. Thapsigargin-stimulated I(SOC) was also measured in freshly isolated rat mesenteric artery smooth muscle cells (MASMC). Members of the transient receptor potential (TRP) family of nonselective cation channels, TRPC1, TRPC4, and TRPC6, were detected by reverse transcription-polymerase chain reaction and Western blot in both A7r5 cells and MASMC. TRPC1 expression was reduced in a stable A7r5 cell line expressing a small interfering RNA (siRNA) or by infection of A7r5 cells with an adenovirus expressing a TRPC1 antisense nucleotide sequence. Thapsigargin-stimulated I(SOC) was reduced in both the TRPC1 siRNA- and TRPC1 antisense-expressing cells, suggesting that the TRPC1 channel contributes to the I(SOC)/CCE pathway.

Exercise training improves lung gas exchange and attenuates acute hypoxic pulmonary hypertension but does not prevent pulmonary hypertension of prolonged hypoxia.

Our laboratory has previously shown an attenuation of hypoxic pulmonary hypertension by exercise training (ET) (Henderson KK, Clancy RL, and Gonzalez NC. J Appl Physiol 90: 2057-2062, 2001), although the mechanism was not determined. The present study examined the effect of ET on the pulmonary arterial pressure (Pap) response of rats to short- and long-term hypoxia. After 3 wk of treadmill training, male rats were divided into two groups: one (HT) was placed in hypobaric hypoxia (380 Torr); the second remained in normoxia (NT). Both groups continued to train in normoxia for 10 days, after which they were studied at rest and during hypoxic and normoxic exercise. Sedentary normoxic (NS) and hypoxic (HS) littermates were exposed to the same environments as their trained counterparts. Resting and exercise hypoxic arterial P(O2) were higher in NT and HT than in NS and HS, respectively, although alveolar ventilation of trained rats was not higher. Lower alveolar-arterial P(O2) difference and higher effective lung diffusing capacity for O2 in NT vs. NS and in HT vs. HS suggest ET improved efficacy of gas exchange. Pap and Pap/cardiac output were lower in NT than NS in hypoxia, indicating that ET attenuates the initial vasoconstriction of hypoxia. However, ET had no effect on chronic hypoxic pulmonary hypertension: Pap and Pap/cardiac output in hypoxia were similar in HS vs HT. However, right ventricular weight was lower in HT than in HS, although Pap was not different. Because ET attenuates the initial pulmonary vasoconstriction of hypoxia, development of pulmonary hypertension may be delayed in HT rats, and the time during which right ventricular afterload is elevated may be shorter in this group. ET effects may improve the response to acute hypoxia by increasing efficacy of gas exchange and lowering right ventricular work.

Systemic oxygen transport in rats artificially selected for running endurance.

The relative contribution of genetic and environmental influences to individual exercise capacity is difficult to determine. Accordingly, animal models in which these influences are carefully controlled are highly useful to understand the determinants of intrinsic exercise capacity. Studies of systemic O(2) transport during maximal treadmill exercise in two diverging lines of rats artificially selected for endurance capacity showed that, at generation 7, whole body maximal O(2) uptake ((.)V(O(2)(max)) was 12% higher in high capacity (HCR) than in low capacity runners (LCR) during normoxic exercise. The difference in (.)V(O(2)(max) between HCR and LCR was larger during hypoxic exercise. Analysis of the linked O(2) conductances of the O(2) transport system showed that the higher (.)V(O(2)(max) was not due to a higher ventilatory response, a more effective pulmonary gas exchange, or an increased rate of O(2) delivery to the tissue by blood. The main reason for the higher (.)V(O(2)(max) of HCR was an increased tissue O(2) extraction, due largely to a higher tissue diffusive O(2) conductance. The enhanced tissue O(2) diffusing capacity was paralleled by an increased capillary density of a representative locomotory skeletal muscle, the gastrocnemius, in HCR. Activities of skeletal muscle oxidative enzymes citrate synthase and beta-HAD were also higher in HCR than LCR. Thus, the functional characteristics observed during exercise are consistent with the structural and biochemical changes observed in skeletal muscle that imply an enhanced capacity for muscle O(2) uptake and utilization in HCR. The results indicate that the improved (.)V(O(2)(max) is solely due to enhanced muscle O(2) extraction and utilization. However, the question arises as to whether it is possible to maintain a continually expanding capacity for O(2) extraction at the tissue level with successive generations, without a parallel improvement in the capacity to deliver O(2) to the exercising muscles.

Arterial endothelial function in a porcine model of early stage atherosclerotic vascular disease.

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in the United States and is projected to become the leading cause of mortality in the world. Atherosclerosis is the most important single factor contributing to this disease burden. In this study, we characterize relationships between endothelial dysfunction and vascular disease in an animal model of diet-induced, early-stage atherosclerotic vascular disease. We tested the hypothesis that hypercholesterolaemia induces vascular disease and impairs endothelium-dependent relaxation (EDR) in conduit arteries of adult male Yucatan pigs. Pigs were fed a normal fat (NF) or high fat cholesterol (HFC) diet for 20-24 weeks. Results indicate that, while the HFC diet did not alter EDR in femoral or brachial arteries, EDR was significantly decreased in both carotid and coronary arteries. Sudanophilic fatty streaks were significantly present in the abdominal aorta and common carotid artery. Histopathology revealed increased intima-media thickness (IMT) and foam cell accumulation in Stary Stage I-III lesions in the abdominal aorta, common carotid artery and femoral arteries. In the coronary arteries, the accumulation of foam cells in Stary Stage I and II lesions resulted in a trend for increased IMT. There was no evidence of vascular disease in the brachial arteries. These results indicate that early stages of CVD (Stary Stage I-III) precede decreases in EDR induced by HFC diet, because femoral arteries exhibited foam cell accumulation and an increased IMT but no change in endothelial function.

Effect of exercise on postprandial lipemia following a higher calorie meal in Yucatan miniature swine.

Exercise has been shown to attenuate the postprandial lipemic (PPL) response to a modest kcal high-fat meal in numerous human studies, but has not been fully examined in swine. In addition, the effects of exercise on a high-fat meal of larger magnitude have not been examined in humans or in swine. Thus, the purpose of this study was to examine the PPL response to a single, high-fat/cholesterol (HFC) meal (approximately 3,000 kcal, 1,300 kcal from fat) and determine if exercise attenuates the PPL response. Sedentary, female Yucatan miniature swine (n = 10) completed 3 PPL trials: (1) pre diet (PRE); (2) post HFC diet (POST); and (3) post HFC diet plus exercise (EX, 45 minutes at 75% heart rate maximum). Blood samples were collected before (0 hour) and at 2, 4, 6, and 8 hours after the single HFC meal for PPL analysis. Postheparin lipoprotein lipase (LPL) activity was assessed at 8 hours. While fasting LPL activity was significantly increased with the HFC diet, the PPL response to the HFC meal did not differ depending on diet. Furthermore, the PPL response was not significantly altered with a single session of exercise, perhaps because of the severity of the HFC meal, the sedentary nature of the swine, or because LPL activity was not elevated after exercise. These findings suggest that administration of a HFC meal of this magnitude (approximately 3,000 kcal, 1,300 kcal from fat) will promote significant elevations in postprandial triglyceride (TG) concentrations, overwhelm the adaptive response to a HFC diet (elevated LPL activity), and attenuate the beneficial effects of a single exercise session on this system.