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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have treated 81 patients who had hypertension with slow intravenous infusion of diazoxide (15 mg/min; 5 mg/kg of body weight). Blood pressure was reduced effectively both in patients with severe hypertension (n = 40) and in patients with a hypertensive crisis (n = 34); the decrease of mean arterial pressure (delta MAP) being -17.0% +/- 1.2% (mean +/- SEM) and -19.7% +/- 1.5%, respectively. However, the delta MAP was significantly greater in patients with preeclampsia (-26.0% +/- 3.0%). In all instances BP fell gradually and then decreased only slightly after discontinuation of the infusion. Thus, the potentially hazardous, steep, and exaggerated fall of BP, observed after bolus injections, can be avoided. Electrocardiographic signs of myocardial ischemia were seen in two patients. No other serious side effects were observed. We conclude that, even in patients with a hypertensive crisis, slow infusion is a safe and effective procedure for the reduction of BP.
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PMID:Acute treatment of hypertension with slow infusion of diazoxide. 667 30

Rats of the salt-resistant Sabra strain (SBN) have a more sensitive baroreflex control of heart rate than do normotensive hypertension-prone salt-sensitive (SBH) rats. To test the hypothesis that increased baroreflex sensitivity confers resistance to hypertension, aortic baroreceptor deafferentation (ABD) was performed in 7- to 10-wk-old SBN rats. This treatment reduced the slope of the mean arterial pressure-heart period (MAP-HP) relationship in response to infusions of increasing doses of phenylephrine in conscious rats, from 1.92 +/- 0.21 to 0.66 +/- 0.11 ms X mmHg-1 (P less than 0.01). The latter value did not differ significantly from that of untreated SBH rats (0.56 +/- 0.07 ms X mmHg-1). Treatment of uniphrectomized SBH, SBN-ABD, and sham-operated SBN rats for 3 wk with deoxycorticosterone acetate (DOCA; 25-mg pellet) and 0.9% NaCl + 0.4% KCl (to maintain normal serum K+ values) as drinking fluid caused increases in systolic blood pressure from 126 +/- 3 to 147 +/- 5 mmHg and 104 +/- 6 to 130 +/- 8 mmHg in the former two groups, respectively, but no significant change (105 +/- 3 to 110 +/- 4 mmHg) in SBN rats when measured by an indwelling arterial catheter in the tail artery. The slopes of the MAP-HP relationships of each of the above three groups of rats were not significantly altered by DOCA-salt treatment. It is concluded that a decrease in baroreflex control of the heart by ABD can render SBN rats sensitive to DOCA-salt-induced systolic hypertension.
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PMID:Baroreflex sensitivity and susceptibility to systolic hypertension induced by DOCA-salt in the Sabra rat. 670 79

Studies were performed to evaluate the mechanism involved in the hypertension of moderate renal failure in partially (five-sixth) nephrectomized rats. Cardiac index (CI) was studied by means of the microsphere technique, and systemic vascular resistance (SVR) calculated from the mean arterial resistance MAP/CI, in four groups of experimental animals: (A) partially nephrectomized rats; (B) group A rats chronically treated with the calcium channel blocker verapamil; (C) sham-operated rats; (D) sham-operated rats treated with verapamil. The results demonstrate a significant increase in MAP in group A rats, which was due to a 72% increase in SVR as compared with groups C and D. In group B rats, MAP decreased significantly owing to a marked decrease in SVR (40%) as compared with group A. However, MAP remained higher in group B than in group C. The vascular responsiveness to noradrenaline was studied in group A, group C and group A rats after parathyroidectomy (group A1). An increased pressor responsiveness to noradrenaline was indicated by a shift of the noradrenaline dose-response curve to the left in group A rats as compared with group C rats. This change was corrected after partial nephrectomy. We conclude that hypertension in nephrectomized rats is due to an increase in SVR, and that an increased pressor responsiveness to catecholamines may play a role in this phenomenon. Furthermore, verapamil reduced the hypertension, and parathyroidectomy improved the abnormal sensitivity to noradrenaline in group A rats. These results raise the possibility that an abnormality in calcium metabolism, possibly due to secondary hyperparathyroidism, may be implicated in the hypertension of mildly uraemic rats.
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PMID:Vascular hypersensitivity to noradrenaline: a possible mechanism of hypertension in rats with chronic uraemia. 674 86

In 74 chronic glomerulonephritis (CGN) and 13 hemodialysis patients (HD) blood volume and hemodynamic indices were examined. Significant correlation was observed between MPA and PV in CGN. High PV in high S-Cr group is considered to be correlated with anemia. Salt restriction reduced MAP without the change in BV in the impaired kidney function group in CGN. Volume depletion in HD shifted TPRI to lower level in the group with significant MAP reduction. The results indicate that sodium rather than water will play an important role in this type of hypertension.
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PMID:Hypertension in chronic glomerulonephritis. 675 Jan 90

The present study was performed to compare hemodynamic effect of intravenous Nitroglycerin (TNT i.v.) in 14 patients developing acute hypertension (Group I) and in 7 non hypertensives after open heart surgery (Group II). In all patients, m.a. 56.6 yrs, (10 mitral and/or aortic prosthetic valve replacements, 9 aorto-coronary bypass, 1 open mitral commissurotomy, 1 closure of atrial septal defect) TNT was infused at doses of 0.5, 1, 2 microgram X kg X min. and subsequently at 2 microgram X kg X min. after volume administration (2 + V.A.) to maintain right and left atrial pressure the same as control (P = N.S.). Mean arterial, right and left atrial pressures (MAP, RAP, LAP), cardiac frequency and index (CF, CI and systemic vascular resistance index (SVRI) were monitorized. TNT i.v. resulted in hypertensive patients (Group I) in reduction vs. control of: a) RAP (--20.17%) and LAP (--20.58%) at 0.5 microgram X kg X min. b) RAP (--26.13%), LAP (--27.50%), MAP (--19.94%) and CI (--12.98%) at 1 microgram X kg X X min. c) RAP (--22.47%), LAP (--26.89%), MAP (--24.68%), CI (--12.6%) and SVRI (--17.34%) at 2 microgram X kg X min. When RAP and LAP was maintained by volume administration TNT i.v. (2 microgram X kg X min.) resulted in an even greater increase in CI and a greater decrease in MAP and SVRI ((--22.04% and --24.88% respectively). No significant hemodynamic modification (P less than or equal to 0.05) were observed in non hypertensive patients (Group II) at all doses of TNT i.v. The results confirm a predominant venodilator effect of TNT at low doses and a good effect on arterial resistances at high doses in hypertensive patients. In view of previous reports of differing effects on ischemia TNT i.v. may be preferable to other vasodilator drugs for control of acute post-ECG hypertension, only on condition to maintain an adequate left ventricular filling pressure to prevent a fall of cardiac index. Moreover the absence of significant (P less than or equal to 0.05) hemodynamic modifications in non hypertensive patients may be a further advantage in the treatment of myocardial ischemia with i.v. TNT.
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PMID:[Effect of intravenous nytroglicerin in hypertensive patients during and after open heart surgery (author's transl)]. 678 Apr 1

Baroreflex activity is a determinant of the homeostatic response to alteration in blood pressure. We examined the factors that determine the magnitude of the vasodepressor response to sequential incremental intravenous infusions of sodium nitroprusside (NP), 0.05 to 6.4 micrograms/kg/min, in eight male patients with essential hypertension. Each infusion level was of 10 minutes' duration. Change from control values of mean arterial pressure (delta MAP), heart rate (delta HR) and plasma norepinephrine (delta NE) were obtained at the end of each infusion level. Significant correlations were found between delta MAP vs log dose NP, delta HR vs delta MAP and delta NE vs delta MAP for each patient (p less than 0.05). However, the slopes of these relationships varied widely between subjects and were significantly correlated with the control blood pressure of each patient. In addition, the sympathetic responsiveness, as measured by delta NE vs delta MAP, was inversely correlated with the degree of vasodepressor response seen. Thus, the magnitude of the vasodepressor response was determined by two major factors: 1) the predrug blood pressure, possibly reflecting altered vascular geometry with hypertension; 2) the degree of sympathetic response, which probably acts by mediating the degree of reflex alpha-adrenergic-mediated arteriolar vasoconstriction.
Hypertension
PMID:Baroreflex sensitivity modulates vasodepressor response to nitroprusside. 684 71

The hypertension immediately after open heart surgery for coronary heart disease was chosen to evaluate the suitability of computer-controlled infusion sodium nitroprusside, to improve the circulatory state in heart failure by reducing the impedance to the left ventricular ejection. Sodium nitroprusside produced a prompt reduction of MAP to a preset level and a rise in cardiac index from an average of 2.1 +/- 0.3 to 2.4 +/- 0.4 when infused alone and to 3.1 +/- 0.5 1/min m2 (p less than 0.05, + 48%) after volume was infused to maintain LAP at a constant level to eliminate the effects of preload. The rise in cardiac index was associated with marked decrease in systemic vascular resistance from 2260 +/- 530 to 1415 +/- 280 and 1130 +/- 1130 +/- 270 dyns (p less than 0.005, 63%) respectively. The initial values of SVR correlated well with the fall of SVR (r = 0.78). Our results suggest that systemic vascular resistance is a strong indicator of the vascular responsiveness to vasodilation, the computer-controlled infusion of sodium-nitroprusside being suitable for the "titration" of the high systemic vascular resistance.
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PMID:[Hemodynamic effects of computer-guided blood pressure-lowering with nitroprusside sodium during the postoperative phase after aortocoronary bypass operations]. 698 28

In a prospective, double-blind, intraindividual, cross-over, placebo-controlled multicenter study, clinical and biochemical effects of once daily postprandial dose regimens of 50, 100, and 200 mg spironolactone were investigated in 45 outpatients with primary hypertension, WHO (World Health Organization) Stage I-II. Each of the three active therapy periods, which were randomly allocated to patients, were of 2 months' duration, with intervening placebo periods, Clinical and biochemical parameters, including furosemide-stimulated plasma renin activity (PRA), were recorded at regular intervals. All three spironolactone doses resulted in statistically significant blood pressure (BP) reductions independent of initial pretreatment levels and yielded satisfactory BP control in more than half of the patients. The 200 mg daily dose of spironolactone was found to be more effective than 50 but not 100 mg. When, correlating blood pressure response (delta MAP) to PRA, the profiling for positive spironolactone responders was characterized by high age and low PRA, irrespective of sex. Spironolactone therapy resulted in decreased serum sodium and magnesium values; potassium, creatinine, urate, and triglyceride levels were increased. However, all treatment values were within normal ranges. Side effects were infrequent and mainly of endocrine nature.
Hypertension
PMID:Clinical and biochemical effects of spironolactone administered once daily in primary hypertension. Multicenter Sweden study. 699 72

We used the neck chamber technique to study carotid baroreceptor control of blood pressure in 18 renovascular hypertensive subjects. Carotid baroreceptors were stimulated or deactivated for 2 minutes by applying graded reductions or increases in the neck tissue pressure (NTP) outside the carotid sinuses. The sensitivity of the baroreflex was separately calculated for these two conditions by the coefficients of the linear regressions relating the changes in NTP to the resulting changes in mean arterial pressure (MAP, catheter measurement). Baroreceptor deactivation increased MAP, and the sensitivity of the baroreflex was 0.12 /+- 0.07 in an early (5 to 1 seconds) and 0.32 /+- 0.05 in a late (90 to 120 seconds) phase of the stimulus application. Baroreceptor stimulation reduced MAP, and the baroreflex sensitivity was in this instance 0.66 /+- 0.08 and 0.05 /+- 0.08 respectively. Both these sensitivities were significantly greater than those obtained for the baroreceptor deactivation. These response entirely reproduced those of essential hypertensive subjects, but differed from those of normotensive subjects in whom baroreflex sensitivity was greater for carotid baroreceptor deactivation than for stimulation. Our findings indicate that carotid baroreceptor control of blood pressure undergoes a marked resetting in renovascular hypertension. The similarity of the baroreflex between renovascular and essential hypertension suggests as secondary origin of the resetting in man.
Hypertension
PMID:Carotid sinus baroreceptor control of arterial pressure in renovascular hypertensive subjects. 706 Nov 28

Factors determining vascular resistance were examined in 6 normotensive subjects (NT), 5 with established hypertension (EH) and diastolic pressures greater than 90 mmHg and 7 with borderline hypertension (BH) having pressures intermittently greater than 140/90 mmHg. Using plethysmography, we measured forearm blood flow (FBF), arterial resistance (FAR) and venous compliance (FVC) before and after autonomic blockade with propranolol 0.2 mg/kh, atropine 0.04 mg/kg and phentolamine 15 mg I.V. Subjects with EH had the highest baseline FBF. MAP was increased 18-22% after atropine and propranolol in all 3 groups. Phentolamine decreased MAP -8.9 +/- 2.1% in NT, -6.9 +/-1.2% in BH and -16.5 +/- 1.9% in EH (p less than 0.05). After total blockade, FAR in EH (32.4 +/- 4.8 units) was similar to FAR in TN (31.0 +/- 3.6 units) whereas that in BH remained high (50.2 +/- 3.8 units; p less than 0.01). Baseline FVC was highest in NT, intermediate in BH and lowest in EH and was not altered by autonomic blockade. Non-gravitational exercise for 6 min during upper arm arterial occlusion after autonomic blockade resulted in a residual FAR of 2.3 +/- 0.1 units in NT, 3.8 +/- 0.3 units in BH and 4.2 +/- 1.7 units in EH (p less than 0.01) during reactive hyperemia. Increased FAR in our subjects with BH and EH was probably due to structural vascular alterations. The greater increase in FAR and MAP in EH over that observed in BH has a sympathetic nervous system component.
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PMID:Vasodilator capacity of forearm vessels in hypertension. 711 72


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