Role of renal sympathetic nerves in renal sodium transport in ouabain-hypertensive rats / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the role of renal sympathetic nerves in renal sodium transport in ouabain-hypertensive rats (OHR).</p><p><b>METHODS</b>Sixteen male SD rats with sham renal denervation (Sham-RDNX) and 16 with renal denervation (RDNX) were randomly into normal control group and ouabain group to receive intraperitoneal injection of normal saline (1 ml/kg) and ouabain (27.8 µg/kg) once a day, respectively. Systolic blood pressure (SBP), heart rate and body weight were recorded weekly. Food consumption of the rats was determined twice a week. After a 4-week treatment, blood and 24 h urine samples were collected to measure the serum and urinary concentration of sodium, trace lithium and creatinine. Endogenous creatinine clearance rate (Ccr), fractional excretions of sodium (FENa), fractional excretions of lithium (FELi) and fractional reabsorption of sodium in the postproximal tubules (FDRNa) were calculated. Plasma renin activity was determined by radioimmunoassay. Norepinephrine was extracted from the renal tissue and assayed for norepinephrine content by HPLC.</p><p><b>RESULTS</b>The body weight, food intake and heart rate showed no significant difference among the 4 groups (P > 0.05). After 4 weeks, the SBP of control RDNX group (CDNX) was significantly lower than that of the control Sham-DNX group (Csham)(P < 0.05); the SBP of ouabain RDNX group (ODNX) was also significantly lower than that of ouabain Sham-DNX group (Osham) (P < 0.05); RNDX lowered SBP by about 10 mmHg in both ouabain groups and control groups. The SBP was significantly higher in Osham and ODNX groups than in the corresponding control groups (P < 0.01), also significantly higher in ODNX group than in Csham group (P < 0.01). Ccr showed no significant difference among the 4 groups(P > 0.05). FENa, FELi and FDRNa were significantly lower in ouabain groups than in the corresponding control groups (P < 0.05, P < 0.01, P < 0.05), but FENa, FELi and FDRNa of ODNX group were similar with those of Osham group (P > 0.05); FENa , FELi and FDRNa were similar between CDNX and Csham groups (P > 0.05). The plasma renin activity was comparable between the 4 groups (P > 0.05). Renal norepinephrine level was markedly reduced in RDNX group compared with that in Sham-RDNX group in both ouabain and control groups (P < 0.01).</p><p><b>CONCLUSION</b>The increase of proximal tubule sodium reabsorption in OHR is not dependent on the renal sympathetic nerve.</p>

Gene characterization of E6 and E7 gene of human papillomavirus of 15 cervical cancer in Beijing / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>Conducting the gene characterization of the E6 and E7 gene of human papillomavirus 16 (HPV16) isolated from 15 cases of cervical cancer at Beijing.</p><p><b>METHODS</b>Overlapping primers were designed according to the full-length genomes of E6 and E7 from the GenBank and PCR was used to amplify the E6 and E7 fragments. TA clone was used to select a purified clone in order to have better and valuable sequencing results. Nucleotide and amino acid sequence were analyzed by the Sequencer, Bioedit, Mega et al.</p><p><b>RESULTS</b>8 of 15 (8/15) cervical samples contained HPV E6 and E7 gene, and 4 had Asian type like and 4 had Europe prototype like. There were two nucleotide mutation at E6 position 178 (T-->G,D25E) and at E7 position 647 (A-->G, N29S) in 4 Asian type like viruses. There were one nucleotide mutation at E6 position 335 (C-->T, H78Y) in 1 of 4 Europe prototype like virus. In the cervical cancer samples, 8 of 15 contained the HPV16E 6 and E7 gene. HPV16 E6 and E7 can not be detected in denosquamous carcinoma and adenocarcinoma.</p><p><b>CONCLUSION</b>HPV16 is the main etiology of the cervical carcinoma. The HPV16 infectious ratio of squamous carcinoma is more than the ratio of adenocarcinoma. 178th nucleotide in E6 gene is the very important site to distinguish the Asia and the Europe prototype strain like. 178 nucleotide in E6 and 647 nucleotide in E7 are the frequent mutation site in cervical carcinoma. Analysis based on the E6 and E7 gene sequence of HPV 16 isolates suggests that naturally occurring sequence variants of E6 and E7 gene may have identify the oncogenic properties.</p>

Contribution of endothelin and its receptors to ouabain-induced hypertension in rats / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of endothelin and its receptors on ouabain-induced hypertension in rats.</p><p><b>METHODS</b>Male Sprague-Dawley (SD) rats were treated with ouabain or saline for 6 weeks and their systolic blood pressure (SBP) were recorded weekly. At the end of 2, 4 and 6 weeks, respectively, the plasma and left ventricle endothelin contents were measured by radio-immunoassay, and real-time quantitative RT-PCR was employed to determine the mRNA level of endothelin type A receptor (ETAR) and type B receptor (ETBR) in the left ventricle, and the protein expressions of ETAR and ETBR were examined by immuno-histochemistry.</p><p><b>RESULTS</b>After 4 weeks of intraperitoneal ouabain injection, the mean SBP in ouabain group increased till reaching a level significantly higher than that in the control group after 6 weeks (P<0.001). The plasma and left ventricle endothelin contents were significantly increased after 2 weeks of ouabain injection (P<0.01), and similarly, increased ETAR mRNA was observed. After 4 weeks of treatment, ETAR mRNA was increased continuously and the protein expression of ETAR upregulated in ouabain group as compared with the control group. The transcription and protein expression of ETBR were not altered by ouabain treatment.</p><p><b>CONCLUSION</b>Before detectable blood pressure elevation occurs, endothelin concentration and ETAR can be already upregulated in ouabain-induced hypertensive rats, suggesting that endothelin might be involved in the cardiovascular effects of ouabain via an action on ETAR.</p>

Changes in renal sodium transport during hypertension development in ouabain-hypertensive rats / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the changes in renal sodium transport during development of hypertension in ouabain-hypertensive rats (OHR) and further elucidate the role of ouabain in the pathogenesis of hypertension.</p><p><b>METHODS</b>Eighty male SD rats weighing 80-100 g were randomized equally into normal control and ouabain groups and treated with intraperitoneal injection of normal saline (1 ml/kg) and ouabain (27.8 microg/kg) once daily, respectively. Systolic blood pressure (SBP) and body weight of the rats were recorded weekly. One week before sacrifice scheduled at weeks 2, 4, 6 and 8, respectively, the rats were individually housed in metabolic cages to determine food consumption twice. Blood and 24-hour urine samples were collected to measure serum and urine concentration of sodium, trace lithium and creatinine. Endogenous creatinine clearance rate (Ccr), fractional excretions of sodium (FENa), fractional excretions of lithium (FELi) and fractional reabsorption of sodium in the distal tubules (FDRNa) were calculated.</p><p><b>RESULTS</b>The body weight and food intake between ouabain groups and control groups were comparable during the experiment (P>0.05). Blood pressure was also comparable in the two groups after 2 weeks (P>0.05). At week 4, however, blood pressure of ouabain group was significantly higher than that of the control group (P<0.001) and increased in a dose-dependent manner. The SBP in ouabain group appeared to reach a plateau at week 7. Ccr and plasma sodium (PNa) were similar in the 2 groups during the experiment (P>0.05). FELi was significantly lower at weeks 2, 4 and 6 in ouabain group than in the control group (P<0.01), and FELi decrement in ouabain group was accompanied by reduced sodium excretion. FENa was significantly lower at week 4 in ouabain group than in the control group (P<0.05), but this difference was not significant in weeks 2 and 6 (P>0.05). At weeks 2, 4 and 6, ouabain group showed significantly lower FDRNa than the control group (P<0.05), suggesting the compensation of the distal nephron segments. After 8 weeks, FENa, FELi and FDRNa were similar between the two groups (P>0.05).</p><p><b>CONCLUSIONS</b>Ouabain can increase renal proximal tubule reabsorption of sodium and consequently decrease renal sodium excretion in OHR, which can contribute to alteration of the pressure-natriuresis relationship in OHR, and play an important role in the development and maintenance of hypertension of OHR.</p>

Effect of ouabain on cardiac function and myocardium ultrastructure of rat / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the changes in rat cardiac function and myocardium ultrastructure in response to ouabain treatment.</p><p><b>METHODS</b>Twenty-four male SD rats were randomized into two equal groups to receive daily intraperitoneal injection of ouabain or saline for 4 consecutive weeks, and their systolic blood pressure (SBP) was recorded weekly. After 4 weeks of injection, echocardiography was performed and the hemodynamic parameters were measured by invasive cardiac catheterization, and the changes in myocardium ultrastructure observed using transmission electron microscopy.</p><p><b>RESULTS</b>After 4 weeks of ouabain injection, no significant changes in the mean SBP occurred in comparison with the saline group, but echocardiographic examination showed significant increases in the left ventricular end-diastolic and end-systolic diameters, septum thickness, posterior wall thickness, left ventricular mass and isovolumetric relaxation time but significantly lowered E/A ratio, ejection fraction and fractional shortening after ouabain treatment (P<0.05). Invasive monitoring revealed significant attenuation of the left ventricular developed pressure, rate of pressure development (+dp/dt) and rate of pressure decay (-dp/dt), and increment of the left ventricular end diastolic pressure. Myofibrillar fragmentation, swelling of the cardiac myocytes, absence of the Z line, increases of the mitochondria and collagen fibers were found in ouabain group by transmission electron microscopy.</p><p><b>CONCLUSION</b>Ouabain can induce left ventricular enlargement, cardiac wall thickening, myocardial ultrastructural alterations, systolic and diastolic dysfunction in rats before blood pressure elevation is detected, indicating that ouabain can directly cause cardiac damage in rats.</p>

Renal sodium handling in ouabain-hypertensive rats / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate renal sodium handling of ouabain-hypertensive rats and the role of renal sodium handling in pathogenesis of hypertension using endogenous trace lithium as a marker of proximal sodium reabsorption.</p><p><b>METHODS</b>Forty male Sprague-Dawley (SD) rats weighting 180-220 g were equally divided into normal control group and ouabain group randomly. Rats were infused with normal saline 1 ml/ (kg x d) or ouabain 27.8 microg/ (kg-d) intraperitoneally once a day respectively. Systolic blood pressure (SBP) and body weight were recorded weekly. Rats were sacrificed after 2 and 6 weeks respectively. Blood and 24 hour urine sample were collected to measure the serum and urinary concentration of sodium, potassium, trace lithium, and creatinine. Endogenous creatinine clearance rate (Ccr), fractional excretions of sodium (FE(Na)), and fractional excretions of lithium (FE(Li)), the ratios of urinary lithium to sodium (U(Li)/U(Na)), the ratios of urinary potassium to sodium (U(K)/U(Na)), and fractional reabsorption of sodium in the postproximal tubules (FDR(Na)) were also calculated. All were studied on their normal diet and ate salt freely.</p><p><b>RESULTS</b>Blood pressure had no significant difference in these two groups after 2 weeks (P > 0.05); After 4 weeks, however, blood pressure was significantly higher in ouabain group than in control group (P < 0.01). Body weight of rats had no significant difference during the experiment period (P > 0.05). Ccr and FE(Na) were similar in these 2 groups (P > 0.05). FE(Li), U(Li)/U(Na), U(K)/U(Na), and FDR(Na) of ouabain group were significantly lower than control group after 2 and 6 weeks (P < 0.05, P < 0.01, P < 0.001 respectively).</p><p><b>CONCLUSION</b>The reabsorption of sodium increases in the proximal tubule in ouabain-hypertensive rats, and such increase occurs before the development of hypertension. Therefore, increase of proximal reabsorption of sodium may be involved in the pathogenesis of ouabain-induced hypertension.</p>

A novel hormone found in circulation--endogenous ouabain / 中国医学科学院学报

Endogenous ouabain (EO) is a recently found hormone that may be secreted from adrenal cortex. As an endogenous mammalian analogue of cardiac glycosides and an inhibitor of the sodium pump, it regulates the body fluid balance, urine sodium extraction and vasoconstrictive tone, and thus plays an important role in the pathogenesis of hypertension and some other cardiovascular disorders. This articke reviews its biological features, receptor and antibody, detection, effects on diseases and relationship with endothelial cells.

An epidemiological study on essential hypertension in northern and western areas of China / 中华流行病学杂志

<p><b>OBJECTIVE</b>To understand the epidemiological characteristics of essential hypertension in the northern and western areas of China.</p><p><b>METHODS</b>A community-based sampling survey.</p><p><b>RESULTS</b>Rates of awareness, treatment and control were 78.6%, 59.7% and 5.9%, respectively. About half of the diagnosed and treated patients took antihypertensive medicine irregularly before the survey was carried out.</p><p><b>CONCLUSION</b>It is necessary to carry out education, prevention and control on hypertension and to establish a series of standards for the management and treatment on cases of hypertension.</p>

The roles of carbon monoxide on hypoxic pulmonary vasoconstriction / 中国应用生理学杂志

<p><b>AIM AND METHODS</b>To study the roles of carbon monoxide on hypoxic pulmonary vasoconstriction (HPV) by investigating the effects of exogenous carbon monoxide and heme oxygenase inhibitor ZnPPIX on hypoxic vasoconstriction reaction of isolated rat pulmonary arterial rings (PAR).</p><p><b>RESULTS</b>Hypoxia caused constriction in PAR preconstricted by PE. Both ZnPPIX and carbon monoxide inhibited hypoxic pulmonary constriction significantly by increasing the cGMP level after hypoxia.</p><p><b>CONCLUSION</b>ZnPPIX and exogenous carbon monoxide can inhibit HPV. The reduction of cGMP induced by the decreased of CO may be one of reasons of HPV.</p>

Vasodilative action of carbon monoxide on rat pulmonary artery in vitro / 生理学报

The present study investigates the vasodilative action of carbon monoxide on rat pulmonary artery in vitro. After isolation of the pulmonary artery rings (PAR) from Wistar rats, an ACh concentration-response curve was generated; the PARs were incubated with the NOS inhibitor L-NAME (30 micromol/L, n=10) or the heme oxygenase inhibitor ZnPPIX (10 micromol/L)+L-NAME (30 micromol/L, n=10) for 30 min. After that, a second ACh concentration-response curve was elicited. Other isolated PARs were randomly divided into two groups: endothelium-intact group (n=8) and endothelium-denuded group (n=8). The effect of exogenous carbon monoxide (CO) on pulmonary arterial vessel tone was observed. The results showed that ACh induced a concentration-dependent pulmonary vasorelaxation. This relaxation disappeared after endothelium was denuded. The ACh induced relaxation was attenuated after pretreatment with 30 micromol/L L-NAME, and attenuated further after pretreatment with 10 micromol/L ZnPPIX+30 micromol/L L-NAME. Exogenous carbon monoxide relaxed pulmonary artery in both the endothelium-intact group and the endothelium-denuded group. These data suggest that ZnPPIX inhibits ACh induced endothelium-dependent pulmonary artery relaxation and that CO is an endothelium-derived relaxation factor, and exogenous CO can relax pulmonary artery.