ISSN:0194-911X    

出版商:OVID    

年代:1980

数据来源: OVID

ISSN:0194-911X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

SUMMARY The effect of removing a renal artery clip 14 to 18 days after its application was studied in twokidney, one clip hypertensive rats. Blood pressure decreased to a normotenslve level within 24 hours after the removal of the clip. The cardiovascular effects of reapplication of the clip and infusion of renin, angiotensin II, and norepinephrine were assessed at that time. Reapplication of the clip to the undipped renal artery was followed in 1 hour by an increase in blood pressure to the level of sham-operated renal hypertensive rats. After reapplication of the clip, plasma renin activity increased to the same level as after the initial application. Application of the clip to the contralateral renal artery did not affect blood pressure and failed to increase plasma renin activity. It appears that renin release is a prerequisite for the rapid rise of blood pressure after reapplication of the clip. The infusion of renin, angiotensin II, and norepinephrine for 90 minutes caused an enhanced blood pressure response similar to that observed following reapplication of the clip. The increase in blood pressure in control rats was associated with bradycardia, which was absent in undipped rats. The enhanced response of undipped rats to an infusion of renin was abolished by pithing. It is concluded that removal of a renal artery clip unmasks a hyperreactivity of the cardiovascular system to reapplication of the clip.

ISSN:0194-911X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

SUMMARY Understanding the connection between sympathetic activity and essential hypertension is still rudimentary. We studied interrelationships of plasma catecholamines, plasma renin activity (PRA), aldosterone, sodium intake, and therapeutic response of 20 normal renin hypertensives. Based on plasma norepinephrine (NE), this population fell into two distinct subsets. The 11 patients in the "normal" NE subset had a basal NE of 257 ± 49 pg/ml (vs 250 ± 62 pg/ml in normotensives), while nine patients in the "high" range NE group averaged 522 ± 125 pg/ml. Both NE subsets showed significant correlation between mean arterial pressure (MAP) and NE. Only the "normal" NE subset showed significant correlation between MAP and PRA, and MAP and aldosterone. Correlations between changes in Na+excretion and NE, PRA, and aldosterone were all negative and statistically significant. Blood pressure was controlled in eight of 11 "normal" NE patients but only in one of nine "high" NE patients by restriction of Na+intake and/or use of a diuretic.

ISSN:0194-911X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

SUMMARY Urinary norepinephrine (UNE) excretion rate and venous plasma norepinephrine (PNE) concentrations were studied in 266 normotensive and 107 essential hypertensive men and women under conditions of volume expansion with 2 liters of intravenous normal saline over 4 hours, and volume contraction with a 10 mEq sodium diet and 120 mg oral furosemide. The UNE excretion rate was correlated with age in normal women only. In men, and in hypertensives of both sexes, the relationship appeared to be biphasic. The PNE concentration was not correlated with age in the hypertensive subjects. Insufficient numbers of older subjects were available to exclude absolutely such a relationship among normals. The UNE and PNE were influenced by volume expansion and contraction in both normals and hypertensives; however, normals exhibited a correlation between UNE and blood pressure as well as consistent correlations between UNE and PNE, neither of which were observed in the hypertensives. Hypertensive women generally had greater UNE and PNE values than normal women or hypertensive men. Hypertensive women may have altered sympathetic activity.

ISSN:0194-911X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

SUMMARY Plasma catecholamine and renln activity levels were measured across a range of dietary sodium intakes (10-300 mEq/day) In 20 normal male volunteers. Supine plasma norepinephrine levels presented a triphasic pattern in relation to urine sodium, whereas epinephrine levels were Dot significantly altered by sodium intake, and renin showed the well-known hyperbolic relationship to urine sodium excretion. Highest supine norepinephrine values occurred at low salt intakes, the lowest when sodium excretion was between 100 and 180 mEq/day, and intermediate when sodium excretion was greater than 180 mEq/day. These findings show that sodium intake is an important consideration in the interpretation of plasma norepinephrine levels.

ISSN:0194-911X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

SUMMARY A combined transmission (TEM) and scanning (SEM) electron microscopic study was performed on aortae of deoxycorticosterone-salt (DOC-salt)-treated rats and spontaneously hypertensive rats (SHR) to compare the effects of hypertension as well as its reversal on the aortic intima. To best reproduce the in riro state of the vasculature, rats were perfusioD-fixed at pressures corrected for each individual animal (30 mm Hg below measured systolic pressure). The intimal alterations were focal and thus were best appreciated with the combined use of SEM and TEM. Qualitatively, both models of hypertension showed similar intimal changes, which consisted of subintimal thickening due to an accumulation of both extracellular material and cells. Subendothelial cells with a morphology indicating a blood-borne origin were present simultaneously with cells derived from the vessel wall. The increased subendothelial extracellular material included precipitated plasma proteins, reticulated basement membrane, collagen fibers, and fragments of elastln. Increase in the height of endothelial cells with distortion of nuclear shape was prominent. Withdrawal of DOC-salt combined with low-salt diet for 11 weeks did not result in a discernible regression of these intimal changes despite normalization of blood pressure. We conclude that vascular injury, once induced, may be difficult to reverse and suggest that areas of prior damage may serve as foci for later vascular complications.

ISSN:0194-911X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

SUMMARY The renal resistance vessels of the mature spontaneously hypertensive rat (SHR) exhibit increased reactivity to vasoconstrictor agonists. This could be a cause or consequence of hypertension. We have compared vascular reactivity in isolated perfused kidneys from 46-day-old SHR and from normotensive control rats. The amplitude of responses in kidneys from the SHR to angiotensin II, barium chloride, or norepinephrine was not different from the control. Therefore, increased reactivity of the renal vascular smooth muscle cannot be an early pathogenic mechanism in spontaneous hypertension. Responses evoked by 5- hydroxytryptamine (serotonin) were of a greater amplitude in the SHR than in the control kidney. However, this difference was due to an interaction of serotonin with the sympathetic nerves, as it was abolished by treatment of the rats with 6-hydroxydopamine. Responses induced by electrical stimulation of the renal sympathetic nerves were also of greater amplitude in SHR than in control kidneys, both before and after the blockade of norepinephrine disposition mechanisms. Nerve stimulation evoked a greater efflux of endogenous norepinephrine from kidneys of the SHR than from those of control rats. Thus, the increased reactivity of the SHR kidney to renal nerve stimulation is due to an augmented release of endogenous norepinephrine. This could be an important factor in the early development of hypertension.

ISSN:0194-911X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

SUMMARY Conscious nonnotensive and two-kidney, one clip Goldblatt hypertensive dogs were studied to determine the influence of the sympathetic and renin-angiotensin systems on the blood pressure and renal blood flow. Renal blood flow was monitored in a single kidney of the normotensire dogs and in the contralateral kidney of the hypertensive dogs. Saralasin was infused intravenously (i.v.) at 1 $g/kg/min for 15 minutes in untreated and guanethidine-treated animals. Guanethidine (i.v.) decreased blood pressure (BP) in the hypertensives at X = 16 days after Goldblatt clamp application, but not in the normotenslves, and did not affect renal blood flow or vascular resistance in either group. Saralasin produced approximately the same BP decrease in both untreated and guanetbidine-treated hypertensives at X = 12 days after Goldblatt clamp application; the combined effect of the drugs was greater than saralasin alone. Blood flow and vascular resistance of the hypertensives' contralateral kidney were not significantly affected by saralasin in these experiments. No sustained effect on BP or renal blood flow was obtained with saralasin in the normotensires. Administration of furosemide was utilized to increase plasma renin activity (PRA) in another series of experiments. In both normotensives and hypertensives, PRA was elevated at 2-3 hours after furosemide application, being greater in the hypertensives. When the renin-angiotensin system was activated in this manner, saralasin had a significant hypotensive and renal vasodilator effect in the hypertensives, but not in the normotenslves.

ISSN:0194-911X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

SUMMARY Arteries and veins of hypertensive rabbits were examined 8 weeks after partially constricting the abdominal aorta above both kidneys, and compared with those from sham-operated animals. Structural and functional changes in blood vessels after 2 weeks, when the arterial pressure first attained a new elevated level, have been described previously, and are now compared with changes 6 weeks later. The increase in blood vessel mass could be correlated with an increase in deoxyribonucleic acid (DNA) content. In contrast to the status at 2 weeks postoperatively, there was no increased uptake of3H-thymidine,3H-proline, or3H-lysine at 2 months. Furthermore, at this time cell nuclei labeled with 'H-thymidine were infrequent. Some vessels showed evidence of change in the physical characteristics of their wall. Only minimal changes were observed in those parameters of adrenergic nerve function measured — neuronal3H-norepinephrine uptake and vessel wall catecholamine content — that had been markedly changed at 2 weeks. The results of this work, together with those of other studies of this model, suggest two phases of response of the arterial wall to pressure rise: an initial dynamic proliferative cellular response mainly of vascular smooth muscle associated with changes in adrenergic neuronal parameters, and a subsequent equilibrium phase characterized by an increased number of smooth muscle cells, some changes in the extracellular components, and minimal changes in the adrenergic Innervation.

ISSN:0194-911X    

出版商:OVID    

年代:1980

数据来源: OVID