摘要:

Vascular responses to norepinephrine (NE) are potentiated in the presence of serotonin (5-HT) and are attenuated by previous exposure to 5-HT. This study was designed to determine whether alterations in the interactions of these agonists occur in renal hypertension. Helical strips of femoral artery from two-kidney, one clip (2K1C) hypertensive and control rabbits were mounted in muscle baths for isometric force recording. Arterial strips from 2K1C rabbits were more sensitive to 5-HT than were those of control rabbits. The sensitivities of these two groups of vessels to NE were not significantly different. The 5-HT potentiation of NE was present at lower 5-HT concentrations in vessels from 2K1C rabbits than in those from control rabbits. Previous exposure to 5-HT attenuated NE responses of arteries from 2K1C less than it did those of control rabbits. Although 5-HT had little effect on loading of cellular stores of calcium in the resting muscle, previous 5-HT exposure attenuated calcuim influx during an NE response, and this attenuation was not as great in vascular smooth muscle from the hypertensive animal as it was in that from the normotensive control. These results indicate that in vascular smooth muscle cells from 2K1C rabbits the potentiating action of 5-HT is increased, due to the increased sensitivity to this agonist, and the attenuating action is decreased due to a greater calcium influx during NE stimulation.

ISSN:0263-6352    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Arterial blood pressure and renal function of both clipped and non-clipped kidneys of benign two-kidney, one clip (2K1C) Goldblatt hypertension were evaluated in order to determine whether high-salt intake alters the course of the development and magnitude of hypertension or influences renal function. The administration of 0.9% sodium chloride as a drinking solution for 3 weeks suppressed plasma renin activity (PRA) and kidney renin content of the clipped kidney to normal values. Despite suppression of PRA and kidney renin content, the saline-drinking clipped rats still developed hypertension of the same magnitude as the water-drinking clipped rats. However, the onset of hypertension was delayed by 4 days. Urine flow, glomerular filtration rate (GFR) and sodium excretion rate from the clipped kidneys of the saline-drinking clipped rats were higher than the corresponding values in the water-drinking rats, and approached those observed in control animals. Thus, the high-salt intake which was associated with suppression of the activity of the renin-angiotensin system delayed the onset of, but not the final magnitude of, the hypertension. In addition, kidney function in the clipped kidneys of saline-drinking clipped rats was enhanced compared with that observed in the water-drinking clipped rats.

ISSN:0263-6352    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

After dosage titration from the age of 1 month to the age of 3 months, spontaneously hypertensive rats (SHR) were treated with pinacidil 10 mg/kg daily until the age of 6 or 12 months. Morphometric data were obtained from the treated SHR as well as from untreated age-matched SHR and normotensive Wistar-Kyoto rats (WKY) at these two developmental stages. Heart:body weight ratios and media:lumen ratios for resistance vessels were determined. Vessels obtained from the mesenteric region were investigated on a myograph. Vessels from heart, kidney and lung were investigated by morphometric analysis of histological sections, only specimens from 12-month-old rats were used. In SHR no effects of either ageing or treatment were detectable, although their blood pressure had been effectively held at normotensive levels throughout the life of the treated animals from the age of 3 months. With the exception of the media index of the pulmonary vessels, which was not statistically different from treated or control SHR, the WKY morphological parameters were significantly lower. In conclusion, pinacidil normalized blood pressure without complications, but this did not affect SHR cardiovascular structure. It is suggested that development of this strain-specific enlargement can only be modified if blood pressure is kept at hypotensive levels, or if the effect of a hitherto unidentified causative factor is antagonized by more-specific pharmacological treatment.

ISSN:0263-6352    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Exchangeable sodium is lower than normal in young male patients with essential hypertension. This may reflect a primary abnormality of sodium metabolism, or natriuresis caused by sodium-independent elevation of arterial pressure. To investigate this question, 31 normotensive men with positive and 31 normotensive men with negative family history of essential hypertension were studied. Blood pressure tended to be higher in the former (121/78 ± 9/8 (s.d.) versus 113/74 ± 11/9mmHg; P < 0.005); mean age, urinary sodium or potassium excretion, plasma sodium, potassium, renin activity or aldosterone levels and creatinine clearance were comparable. Exchangeable sodium and blood volume were also similar in the two groups, when expressed in absolute values (3113 ± 306 versus 3044 ± 242 mmol and 4902 ± 581 versus 4769 ± 579 ml, respectively) or in relation to body surface area (100.8 ± 7.1 versus 100.2 ± 6% and 103.8 ± 12.2 versus 102 ± 11.3%). In both groups, exchangeable sodium and blood volume were unrelated to arterial pressure. The body sodium/blood volume state is normal in normotensive subjects with positive family history. The low exchangeable sodium of young patients with essential hypertension does not appear to reflect a primary familial abnormality of body sodium metabolism.

ISSN:0263-6352    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

In a double-blind, placebo-controlled, crossover study in 16 hypertensives, 4 weeks of 50 mg hydrochlorothiazide twice daily, caused significant elevations in total plasma cholesterol, high density lipoprotein (HDL)-cholesterol, low density lipoprotein (LDL)-cholesterol, very low density lipoprotein (VLDL)-cholesterol and triglycerides. Significant elevations in fasting plasma glucose and in plasma insulin were observed, but no correlation between individual lipid elevations and either glucose or insulin elevations was apparent. The metabolic effects developed within 2 weeks, and dissipated within 4 weeks. Changes induced within 4 weeks of treatment with hydrochlorothiazide were unaltered at 6 months. Hydrochlorothiazide induces elevation of all lipoprotein cholesterol fractions and VLDL-triglyceride. However, as the important ratio between LDL- and HDL-cholesterol is unchanged, coronary risk may be unchanged.

ISSN:0263-6352    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Fifty-nine healthy omnivores volunteered for a randomized crossover trial with a lacto-ovo-vegetarian (L-O-V) diet. Twenty-one 1-day diet records were kept throughout the project as a means of assessing food and nutrient intakes, and samples of serum and urine were assayed to evaluate change in prostanoid metabolism. While on the L-O-V diet subjects ate more vegetable protein, wholegrain cereals, polyunsaturated oils, fruits and vegetables, and avoided eating meat, fish or poultry. The L-O-V diet contained significantly more polyunsaturated fatty acids, fibre, vitamin C, vitamin E, magnesium, calcium and potassium, and less total protein, saturated fat, monounsaturated fat and vitamin B12 than the control omnivore diet.Changes in nutrient intakes were subjected to principal components analysis to identify dimensions of change in nutrient intakes. Three Factors accounted for 83% of the total variation in dietary intake. Blood pressure changes were significantly and negatively (F=17.4, P < 0.001 for systolic; F=6.09, P=0.02 for diastolic pressure) related to individual scores for only onelFactor-that representing an increase in intake of polyunsaturated fat, fibre, vitamin C, vitamin E, calcium and magnesium, and a fall in intake of protein and vitamin B12. Blood pressure changes were unrelated to change in body weight or sodium intake.Serum and urinary prostanoids were not affected by eating the L-O-V diet.

ISSN:0263-6352    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The purpose of this study was to assess whether two-kidney, one clip (2K1C) renal hypertension can be induced in the marmoset. During the first 3-5 weeks after renal arterial clipping, blood pressure (BP) and plasma renin activity (PRA) increased in approximately one-third of the operated marmosets. However, within 10 weeks after clipping, BP and PRA had returned to control values. There was a significant positive correlation between BP and log PRA 3 and 5 weeks after the operation, but no correlation was observed at 10 weeks. In a selected group of marmosets with the highest values of BP (>140 mmHg; n=4), the converting enzyme inhibitor, enalapril (2 mg/kg s.c.) lowered BP by 58 ±7 (s.e.m.) mmHg when given 3 weeks after clipping. At 18 weeks the response to enalapril was only -17 ± 6 mmHg. These results demonstrate that unilateral renal arterial clipping in marmosets results in a transient renin-dependent hypertension. Marmosets in this initial hypertensive phase could be useful for investigating the antihypertensive effects of inhibitors of human renin.

ISSN:0263-6352    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The possibility that sympathetic pressor responses are modulated by adrenalinemediated facilitation of neuronal noradrenaline release was explored in 17 subjects with borderline hypertension. Infusion of adrenaline, which raised plasma adrenaline by a factor of 8 to 9, augmented the rise in systolic and diastolic arterial pressure induced by standardized cold pressor and isometric exercise tests. The heart rate response to these tests was not affected. When a low dose of propranolol was given on top of the adrenaline infusion before the cold pressor test, the blood pressure response to cold exposure was not different from the response observed when the test was performed during saline infusion. Plasma noradrenaline was higher during adrenaline infusion then during saline infusion, both before and after the cold pressor and isometric exercise tests, and the effect of adrenaline on plasma noradrenaline was antagonized by propranolol. These observations are consistent with the hypothesis that stress levels of circulating adrenaline may amplify sympathetic pressor responses by facilitation of the release of transmitter noradrenaline.

ISSN:0263-6352    

出版商:OVID    

年代:1986

数据来源: OVID