Assessing explicit processes does not influence the magnitude of implicit processes.

Implicit (unconscious) and explicit (strategy) processes have been shown to contribute to visuomotor adaptation. Current methods, such as the Process Dissociation Procedure (PDP) and the Verbal Report Framework (VRF), simultaneously evaluate both implicit and explicit contributions to visuomotor adaptation. It is unclear whether the act of assessing explicit adaptation leads to variations in the magnitude of implicit adaptation observed. To address this question, four groups of participants adapted their reaches to a 40° clockwise visuomotor rotation. Implicit and explicit adaptation were assessed in a PDP-IE group and a VRF-IE group following 3 blocks of rotated reach training trials. In contrast, only implicit adaptation was assessed at the same time points for a PDP-I group and VRF-I group. Results indicated a similar magnitude of implicit adaptation regardless of whether explicit adaptation was assessed or not. Thus, assessing explicit adaptation simultaneously with implicit adaptation following reach adaptation does not influence the magnitude of implicit adaptation established via the PDP and VRF methods.

Zidovudine potentiates local and systemic inflammatory responses in the rat.

The effect of chronic treatment with zidovudine (AZT) on the inflammatory response was examined in the rat. AZT was administered orally for 36 days. On day 35, inflammation was induced by hindpaw injection of 1% carrageenan lambda. Paw edema over a 24-hour period was used as a marker of the local inflammatory reaction. On day 36, quantification of immunoreactive T-kininogen and alpha 1-inhibitor-3 in liver and serum was used to assess the systemic inflammatory response. Albumin was selected as a protein whose concentration is modified only slightly or not at all during the acute-phase response. Animals treated with AZT transiently exhibited significantly greater (18%) paw edema 3 hours after carrageenan injection. AZT treatment alone induced a 1.8-fold increase in serum T-kininogen concentration, but it had no effect on albumin and alpha 1-inhibitor-3. In rats with inflamed paws, AZT administration led to a significant increase in liver (3.4-fold) and serum (1.8-fold) immunoreactive T-kininogen content. Dot blot analysis of total RNA isolated from liver correlated with the protein measurements. Our results indicate that chronic treatment with AZT potentiates the nonspecific local and the systemic inflammatory responses in the rat.

Serum interspecies differences in metabolic pathways of bradykinin and [des-Arg9]BK: influence of enalaprilat.

Among the different enzymes responsible for the metabolism of bradykinin (BK), three peptidases look relevant in vivo: kininase I (KI), which transforms BK into its active metabolite, [des-Arg9]BK; kininase II (KII); and neutral endopeptidase, which inactivate BK and [des-Arg9]BK. The in vitro incubation of BK and [des-Arg9]BK in the serum of four species with or without enalaprilat and the quantification of the immunoreactivity of both peptides at different time intervals allowed the measurement of the kinetic parameters characterizing their metabolic pathways. Highly sensitive chemiluminescent enzyme immunoassays were used to measure the residual concentrations of BK and [des-Arg9]BK. Half-life (t1/2) of BK showed significant difference among species: rats (10 +/- 1 s) = dogs (13 +/- 1 s) < rabbits (31 +/- 1 s) < humans (49 +/- 2 s). t1/2 values of [des-Arg9]BK were also species dependent: rats (96 +/- 6 s) < < rabbits (314 +/- 6 s) = dogs (323 +/- 11 s) = humans (325 +/- 12 s). Enalaprilat significantly prevented the rapid BK and [des-Arg9]BK degradation in all species except that of [des-Arg9]BK in rat serum. Relative amount of BK hydrolyzed by serum KII was given as follows: rabbits (93.7 +/- 14.8%) = rats (83.6 +/- 6.7%) = humans (76.0 +/- 7.5%) > dogs (50.0 +/- 3.9%). Its importance in the hydrolysis of [des-Arg9]BK was 5.2 +/- 0.5% in rats < < 33.9 +/- 1.5% in humans < 52.0 +/- 1.1% in rabbits < 65.1 +/- 3.4% in dogs. The participation of serum KI in the transformation of BK into [des-Arg9]BK was dogs (67.2 +/- 5.3%) > > humans (3.4 +/- 1.2%) = rabbits (1.8 +/- 0.2%) = rats (1.4 +/- 0.3%). Finally, no significant difference on t1/2 values for BK and [des-Arg9]BK could be demonstrated between serum and plasma treated with either sodium citrate or a thrombin inhibitor. These results revealed striking species differences in the serum metabolism of kinins that could address at least partially some of the controversial data related to the cardioprotective role of kinins.

Chloramphenicol and the inflammatory response in the rat. Upregulation of the gene for T2-kininogen in liver.

Recent observations have indicated that cytokine and glucocorticoid mediators of the inflammatory response in mammals interfere with mitochondrial respiratory capacity of cultured cells. Here, we report studies on the effect of the antibiotic chloramphenicol (CAP), a potent mitochondrial protein synthesis and respiratory inhibitor, on the inflammatory response in the rat. CAP was injected daily (i.p.) at doses of 30, 100 and 300 mg kg-1 during a period of 10 days. Acute inflammation was induced on day 10 by s.c. injection of carrageenan into the hindpaws. Paw edema reaction and liver and serum expression of the acute phase protein T-kininogen were used as markers of the local and systemic inflammatory response, respectively. Albumin was selected as a liver protein whose expression is little or not affected in inflamed rats. We found that the swelling process induced locally by carrageenan injection was significantly altered in rats treated with CAP at the dose level of 300 mg kg-1. The inhibitory effect of CAP was transient, extending up to 3 hr after carrageenan injection. CAP was observed also to alter the mitochondrial respiratory capacity of liver cells, reducing cytochrome C oxidase activity up to 50%. In contrast, liver immunoreactive T-kininogen content and the T2-kininogen mRNA steady-state level were found to increase in a dose-related manner in CAP-treated animals. These values were slightly different from those recorded in control rats inflamed with carrageenan. No significant increase of T-kininogen serum content was seen at all dose levels of CAP injected. Among inflamed animals, those exposed long-term to CAP had elevated liver and serum T-kininogen content and t2-kininogen mRNA steady-state levels. Expression of the gene for albumin was not affected in rats treated or not with CAP. The present observations indicate that CAP influences both local and systemic inflammatory responses in the rat.

Effects of captopril and Icatibant on bradykinin (BK) and des [Arg9] BK in carrageenan-induced edema.

The effects of captopril, an angiotensin-converting enzyme inhibitor (ACEI), and a selective B2 kinin receptor antagonist (Icatibant) were examined on the paw edema and tissue contents of bradykinin (BK) and des[Arg9]BK following the intraplantar injection of carrageenan in rats. To this end, BK-like immunoreactivity (BK-LI) and des[Arg9]BK-LI were measured with highly sensitive and specific chemiluminescent enzyme immunoassays. Because pentobarbital significantly reduced the carrageenan-induced edema between 3 and 8 h, experiments were conducted in conscious rats. Icatibant (32.5 nmol/paw; intraplantar) significantly reduced carrageenan-induced paw edema between 3 and 8 h in captopril-untreated rats and at 1 and 3 h in captopril-treated rats (0.2 mg/kg x 5 days, per os). The paw content of BK-LI was increased 10-fold in captopril-untreated and 29-fold in captopril-treated rats 1 h after carrageenan injection. In parallel, des[Arg9]BK-LI was increased 8-fold in captopril-untreated and 24-fold in captopril-treated rats. Icatibant prevented the maximal increases in BK-LI and des[Arg9]BK-LI induced by carrageenan. It is concluded that inhibition of ACE by captopril enhanced the early production of endogenous BK and the edema formation induced by carrageenan through a B2 receptor-mediated mechanism. However, the B2 receptor does not appear to be involved in the late phase of the inflammatory response (from 5 to 24 h) to carrageenan in rats pretreated with ACEI. Although the concentrations of des[Arg9]BK were greater than those of BK, it is unlikely that B1 receptors play a significant role in this model of carrageenan-induced edema.

A role for B1 and B2 kinin receptors in the modulation of T-kininogen during the acute phase response of inflammation.

Kinin antagonists at B1 and B2 receptors were examined on liver and serum concentrations of immunoreactive T-kininogen and its gene expression in a rat model of carrageenan-induced hindpaw edema. Whereas the B2 antagonist, HOE140, dose-dependently inhibited the paw edema induced by intraplantar injection of carrageenan, the B1 receptor agonist [Sar(D-Phe8)des-Arg9]BK and antagonist [Lys(Leu8)des-Arg9]BK were ineffective. On its own, HOE140 (3.25 x 10(-7) mol/ paw, intraplantar) had no effect on liver and serum T-kininogen levels but it significantly enhanced liver T-kininogen concentrations in rats pretreated with carrageenan at 8 and 24 h postinjection. In the liver, the most pronounced effect was seen at 24 h (treated 248 +/- 7 micrograms/g vs. untreated 113 +/- 9 micrograms/g). The same dose of HOE140 increased serum T-kininogen from 1255 +/- 57 to 1696 +/- 83 micrograms/ml at 24 h. HOE140 did not affect tissue albumin content during the same period. Transcript measurements revealed that the steady-state level of liver T2-kininogen mRNA was specifically increased by HOE140 during inflammation. In carrageenan-treated rats, the B1 antagonist [Lys(Leu8)des-Arg9]BK also significantly increased liver T-kininogen at 24 h. The present results support a role for B2 kinin receptors in the early phase of acute phase protein synthesis and of both B2 and B1 receptors in the late phase (24 h). Hence, systemic effects of kinins should be taken into account in the pharmacology and physiopathology of B1 and B2 kinin receptors in inflammation.

Development of digoxigenin-labeled peptide: application to chemiluminoenzyme immunoassay of bradykinin in inflamed tissues.

A new ultrasensitive chemiluminoenzyme immunoassay (CLEIA) using digoxigenin-labeled bradykinin (BK) as a tracer is proposed to quantify kinins in tissue samples. Rabbit polyclonal IgGs anti-BK directed against the C-terminal end were used for the immunoconcentration step along with dioxetane derivative for the revelation step. The sensitivity of the assay for BK was 0.1 fmol/ml with ED50 of 0.78 pmol/ml. This method was applied on extracts of normal and carrageenan-inflamed tissues. The edema produced by the injection of carrageenan in rat hindpaws was associated with a sevenfold increase of immunoreactive kinins in the inflamed paw extract (from 0.021 +/- 0.007 to 0.141 +/- 0.021 pmol/g tissue; p < 0.01), the immunoreactivity corresponded to BK, kallidin, and T-kinin after HPLC separation. When a mixture of inhibitors of kininase I (mergepta) and kininase II (captopril) was coinjected with carrageenan, the carrageenan-induced edema was unaffected but the kinin tissue content was significantly enhanced (0.207 +/- 0.003 pmol/g tissue; p < 0.01). However, the kinin tissue content and the edema response were unaltered by inhibitors given separately. Hence, this highly sensitive assay provides a biochemical evidence that kinins may act as proinflammatory mediators, and highlights a compensatory increase of kininase I and II activities in inflamed tissues.

Characterization of the peripheral action of neuropeptide K on the rat cardiovascular system.

The effects of neuropeptide K (NPK) were measured on mean arterial pressure (MAP) and heart rate (HR) after i.v. injection in urethane-anesthetized rats. NPK (6.5 and 32.5 nmol/kg) produced sustained decreases in MAP and elicited increases in HR. Whereas the NPK-induced tachycardia lasted more than 30 min at 32.5 nmol/kg, a latent and long-lasting bradycardia appeared from 20 min after injection of 6.5 nmol/kg. The initial tachycardia was converted to bradycardia by metoprolol but remained unaffected by hexamethonium, atropine and naloxone. These four treatments, however, prevented the bradycardiac response to NPK at 30 min. Whereas phentolamine, idazoxan, bilateral adrenalectomy and chemical sympathectomy with 6-hydroxydopamine (6-OHDA) preserved the initial tachycardia induced by NPK, they converted the decrease in HR to a tachycardiac response at 30 min. The vasodepressor response to NPK was significantly enhanced by bilateral adrenalectomy, chemical sympathectomy and metoprolol but remained unaffected by all other treatments. Neither the MAP nor the HR responses to NPK were affected by indomethacin. These results suggest that NPK can accelerate HR through non-reflex activation of the sympathoadrenal system. The secondary bradycardia induced by NPK may be due to a vagal reflex while the vasodepressor response to NPK is probably attributable to a direct action mediated by specific receptors on arterial blood vessels. Thus, NPK is considered as the most potent biologically active tachykinin so far described on the rat cardiovascular system.