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

We have investigated relationships between age, blood pressure and intracellular calcium concentration in platelets from normotensives and hypertensives. In normotensives, there were positive correlations between age and platelet intracellular calcium concentration (r = 0.76, P less than 0.001), age and mean arterial pressure (MAP; r = 0.55, P less than 0.01) and MAP and platelet intracellular calcium concentration (r = 0.45, P less than 0.01). Multiple regression analysis revealed that age was the primary determinant of platelet intracellular calcium concentration in normotensives. The effect of MAP on platelet intracellular calcium concentration when adjusted for age was not significant (P = 0.73). In hypertensives, there was no significant relationship between age and platelet intracellular calcium concentration (r = 0.15, P = 0.43), age and MAP (r = 0.17, P = 0.37) or MAP and platelet intracellular calcium concentration (r = -0.27, P = 0.15). Overall, platelet intracellular calcium concentration was significantly higher in hypertensives than in age-matched normotensives (P less than 0.05). Within the age groups examined, platelet intracellular calcium concentration was significantly higher only in younger hypertensives when compared with controls of a similar mean age (P less than 0.001). Thus, age, in addition to hypertension, is an important determinant of platelet intracellular calcium concentration.
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PMID:The effects of age on platelet intracellular free calcium concentrations in normotensives and hypertensives. 166 86

The hemodynamic and electrocardiographic (ECG) effects of pancuronium and vecuronium were compared during high-dose fentanyl anesthesia for coronary artery bypass grafting (CABG) surgery. Forty-eight morphine-scopolamine premedicated patients scheduled for elective CABG were anesthetized with fentanyl (100 micrograms/kg) in divided doses, and either of two muscle relaxants, pancuronium (n = 26; 0.10 mg/kg) or vecuronium (n = 22; 0.09 mg/kg). Hemodynamic data, blood gas samples, and ECG tracings were obtained at the following intervals: (1) control; (2) prior to intubation; (3) 1 minute after intubation; (4) prior to sternotomy; and (5) 1 minute after sternotomy. In the pancuronium group, heart rate (HR), cardiac index (CI), and rate-pressure product (RPP) were increased after induction of anesthesia and following intubation. Eleven patients (42.3%) displayed ischemic ST segment changes. Four patients in this group developed tachycardia and hypertension to an extent requiring pharmacological intervention. Vecuronium-treated patients displayed no increases in HR, MAP, and RPP, and a decrease in CI. Only one patient (5.6%) developed evidence of ischemic ECG changes. Four patients in the vecuronium group, all receiving preoperative beta-blocker therapy, became hypotensive and bradycardic after the induction of anesthesia. The present investigation confirms the increased incidence of myocardial ischemia during high-dose fentanyl-pancuronium anesthesia. Although vecuronium was associated with fewer myocardial ischemic changes, the occurrence of bradycardia and hypotension in some patients receiving preoperative beta-adrenergic blocking drugs remains a concern.
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PMID:Hemodynamic responses to pancuronium and vecuronium during high-dose fentanyl anesthesia for coronary artery bypass grafting. 135 92

In this article, we analyze the blood pressure (BP) threshold for the start of antihypertensive treatment in insulin-dependent diabetes mellitus (IDDM) patients, with particular emphasis on those with persistent microalbuminuria or proteinuria (incipient and overt nephropathy, respectively). In such individuals, there is a clear increase in the prevalence of hypertension and in actual measured BP values that is not observed in normoalbuminuric patients. In 94 young healthy adults (less than 45 yr of age), average mean +/- SD arterial pressure (MAP; diastolic + 1/3 pulse pressure) was approximately 90.0 +/- 8.1 mmHg, closely corresponding to large population studies. In microalbuminuric IDDM patients, MAP values between approximately 105 and approximately 95 mmHg have been found in different studies, and the level has progressively decreased in various studies between 1984 and 1990 with similar BP-measuring techniques. Somewhat higher values are seen in patients with proteinuria, who are also consistently characterized by reduced glomerular filtration rate (GFR). A clear correlation is found between MAP plotted against the increased rate of microalbuminuria (%/yr) in incipient nephropathy and against fall rate of GFR (ml.min-1.mo-1) in proteinuric patients. In the natural history of renal disease, different cutoff points in MAP for start of progression are observed: greater than 95 mmHg for the start of progression of microalbuminuria and greater than 105 mmHg for the decrease in GFR. During antihypertensive treatment, there is reduction or no progression in microalbuminuria with MAP of approximately 90-95 mmHg and only a limited fall in GFR with MAP of approximately 100 mmHg. However, certain antihypertensive drugs (angiotensin-converting enzyme inhibitors) may have specific renoprotective actions, reducing microalbuminuria at rather low BP levels or even independent of BP reduction. The optimal way of monitoring BP may be by 24-h ambulatory recording.
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PMID:Renal factors influencing blood pressure threshold and choice of treatment for hypertension in IDDM. 174 53

Renal functional reserve (renal response to protein loading, RFR) has been suggested as a method to verify the presence of hyperfiltration. This study was designed to evaluate the role of RFR as an indicator of increased glomerular capillary hydrostatic pressure in short-term treated and untreated rats with two-kidney, one-clip Goldblatt hypertension. One month after placing a silver clip, micropuncture studies were performed on the unclipped kidney. Normal rats and three groups of clipped rats [untreated group (HYP), a group treated with captopril (CEI) and a group treated with verapamil (VER) 5 days before the micropuncture studies] were studied. Glomerular hemodynamics and proximal tubular reabsorption were measured in control period and during intravenous administration of glycine (G). In normal rats, G produced afferent and efferent dilation, increases in single nephron plasma flow (SNPF) and single nephron glomerular filtration rate (SNGFR) of 24%. Systemic hypertension in HYP rats was associated with increases in transcapillary pressure gradient (delta P) and SNGFR. In this hyperfiltration state, infusion of G did not modify SNGFR of SNPF defining loss of RFR. The antihypertensive treatment was equally effective in normalizing MAP and delta P in CEI and VER, but only CEI rats responded to G with a 20% increase in SNGFR due to an increase in delta P. The most striking findings were that loss of RFR in both HYP and VER rats was associated with a significant decrease in absolute and proximal fractional reabsorption.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Renal functional reserve in treated and untreated hypertensive rats. 178 41

In an open, randomized, multicenter trial, intravenous nicardipine was compared with sodium nitroprusside in 74 patients with hypertension (mean arterial pressure [MAP] greater than or equal to 100 mm Hg) following coronary artery bypass surgery. Nicardipine was administered as a 2.5- to 12.5-mg bolus followed by a 2 to 4 mg/h infusion, and nitroprusside as a 0.5 to 6.0 micrograms/kg/min infusion. The aim was to reduce MAP to less than 90 mm Hg within 50 minutes and maintain it stable at 85 +/- 5 mm Hg. Nicardipine was effective in 35 of 38 patients (92%), and nitroprusside in 29 of 36 (81%) (NS). The decrease in MAP was not statistically different, but time until reaching the therapeutic end-point was shorter with nicardipine (P less than 0.01). Significant differences follow: increase in heart rate and decreases in mean pulmonary artery, right atrial, and pulmonary capillary wedge pressures were more marked with nitroprusside (P less than 0.01 and P less than 0.05, respectively), whereas elevation of cardiac index and depression of systemic vascular resistance were more marked with nicardipine (P less than 0.01 and P less than 0.05, respectively). Postreduction MAP was more stable with nicardipine, 51% +/- 24% of readings falling within the range 85 +/- 5 mm Hg versus 41% +/- 18% on nitroprusside (P = 0.058). Dose adjustment during the following 24 hours was less frequent with nicardipine, 1.1 +/- 1.6 versus 2.7 +/- 2.6 (P less than 0.01). Transfused blood volume was lower with nicardipine (924 +/- 644 mL) than nitroprusside (1,306 +/- 901 mL) (P = 0.08), despite similar postoperative blood losses.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Comparison of nicardipine and sodium nitroprusside in the treatment of paroxysmal hypertension following aortocoronary bypass surgery. 187 13

The hypothesis that changes in baroreflex function seen in hypertension could be explained by a decreased vascular compliance in the carotid sinus region itself was tested. Six dogs were made chronically hypertensive (MAP = 146.0 +/- 3.3 mm Hg) using a bilateral renal wrap technique, while six other dogs were sham operated and served as normotensive controls (MAP = 125.8 +/- 4.7 mm Hg). Six weeks after the procedure, compliance of the carotid sinus region was measured, and carotid baroreflex control of arterial pressure and heart rate was assessed acutely. Dogs were anesthetized with sodium pentobarbital and the carotid sinus was isolated and perfused at controlled pressures. Vagotomy was performed to eliminate aortic and cardiopulmonary reflex buffering. The carotid sinus pressure (CSP) was changed from 25 to 250 mm Hg in a stepwise fashion, and the corresponding arterial pressure, heart rate and volume changes were recorded. Compliance was determined as the change in volume infused divided by the changes in pressure achieved. Significant differences between the normotensive and hypertensive groups were found in the reflex responses of arterial pressure and heart rate to changes in CSP. Carotid sinus compliance decreased with increasing CSP, but was not different in the two groups. Changes in baroreflex responses seen in mild hypertension occur without significant changes in carotid sinus compliance, and cannot be explained solely by a decreased compliance in the receptor wall.
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PMID:Carotid sinus compliance and baroreflex responses in hypertensive dogs. 193 Aug 51

The immunosuppressive drug cyclosporin A (CsA) frequently induces hypertension, but the mechanism(s) is unknown. Thus, we examined the mechanism(s) by which CsA increases arterial blood pressure (MAP) in the normotensive rat. Three different treatment modalities were used. First, chronic CsA treatment (20 mg/kg/day, s.c., for 1 week) significantly increased MAP from 109.6 +/- 2.3 mm Hg to 125.8 +/- 2.9 mm Hg (P less than .05). Second, subacute i.v. infusion of CsA (20 mg/kg daily for 3 days) increased MAP to even higher values (140.5 +/- 2.3 mm Hg), which correlated significantly with the highest circulating values of the drug. The pressor effect after i.v. infusion appears to be unrelated to endogenous release of catecholamines, because phentolamine, which abolishes the response to exogenous norepinephrine, failed to prevent the CsA-induced pressor response. Third, i.v. bolus injections of CsA (10-20 mg/kg) evoked immediate, dose-dependent and short-lasting increases in MAP (+15-25 mm Hg) in both anesthetized and conscious rats. Ganglionic blockade did not prevent this effect, rather, a 2- to 3-fold increase in amplitude (+40-60 mm Hg) and duration (+30-45 min) of the CsA-induced pressor response was observed in anesthetized rats. Heart rate was not increased significantly by either acute or chronic administration of CsA. Our results suggest that both CsA-induced pressor responses and hypertension are due to a peripheral action unrelated to sympathetic outflow. Furthermore, CsA's hypertensive effect is accompanied by severe morphological changes in the vascular endothelium and smooth muscle cells. In addition, CsA-treated rats showed significantly attenuated vasodilatory responses to prostacyclin and sodium nitroprusside, and increased pressor responses to norepinephrine. Thus, a direct vascular action of CsA is likely to contribute to the alterations on systemic vascular responsiveness, as well as to the hypertensive effect of the drug.
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PMID:Systemic vascular effects of cyclosporin A treatment in normotensive rats. 194 35

1. Abnormalities of the renal dopaminergic system have been implicated in the pathogenesis of hypertension in the spontaneously hypertensive rat (SHR). 2. Both DA-1 and DA-2 receptors are present in renal tubules and blood vessels. DA-1 receptors mediate the renal vasodilatory and natriuretic effects of DA but the contribution of DA-2 receptors to these effects is not known. 3. We therefore studied the effect of a novel and selective DA-1 and DA-2 agonist, pramipexole, on MAP, glomerular filtration rate (GFR), urine flow (V), absolute (UNaV) and fractional sodium (FeNa) excretion in 9-18-week-old SHR. Wistar-Kyoto rats (WKY) served as control. 4. Pramipexole given intravenously (1, 10, 100 micrograms kg body wt-1 min-1) decreased MAP in a dose-related manner to a greater extent in SHR (n = 5) than WKY (n = 6) such that at the highest dose of pramipexole, MAP was similar in both groups. Pramipexole did not alter GFR in either WKY or SHR. Pramipexole increased V in a dose-related manner in both WKY and SHR. At 100 micrograms pramipexole kg body wt-1 min-1, V increased eightfold in both SHR and WKY. In contrast, pramipexole increased UNaV to a greater extent in WKY (5.1-fold) than SHR (3.7-fold). 5. These studies show a differential effect of pramipexole on renal function and MAP in SHR and WKY. Pramipexole has a more potent blood pressure lowering effect in SHR than in WKY. However, the natriuretic effect of pramipexole was greater in the WKY than in the SHR.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of pramipexole, a dopamine-1/dopamine-2 receptor agonist, on sodium excretion and blood pressure in spontaneously hypertensive rats. 198 9

Previous studies from our laboratory have shown that arterial baroreceptor reflex control of lumbar sympathetic nerve activity is blunted in the NaCl-sensitive spontaneously hypertensive rat (SHR-S) compared with either the NaCl-resistant spontaneously hypertensive rat (SHR-R) or the normotensive Wistar-Kyoto (WKY) rat. In the current study, the effect of dietary NaCl supplementation on arterial baroreceptor reflex control of lumbar sympathetic nerve activity and heart rate was assessed in SHR-S and control SHR-R and WKY rats. Male SHR-S, SHR-R, and WKY rats were fed diets containing either 1% or 8% NaCl beginning at 7 weeks of age and were studied at age 9-10 weeks. Arterial baroreceptor reflex-mediated changes in lumbar sympathetic nerve activity and heart rate were recorded in conscious, unrestrained rats during phenylephrine-induced (15-40 micrograms/kg/min) and nitroprusside-induced (15-300 micrograms/kg/min) changes in mean arterial pressure. SHR-S maintained on a 1% NaCl diet had blunted baroreceptor reflex control of lumbar sympathetic nerve activity during acute increases in MAP compared with SHR-R and WKY rats (p less than 0.05). After ingestion of the 8% NaCl diet, this blunting was absent, indicating enhancement of baroreceptor reflex control of lumbar sympathetic nerve activity. SHR-S maintained on a 1% NaCl diet also had blunted arterial baroreceptor control of lumbar sympathetic nerve activity during nitroprusside-induced decreases in mean arterial pressure compared with WKY rats, but this was not significantly altered during ingestion of the 8% NaCl diet.(ABSTRACT TRUNCATED AT 250 WORDS)
Hypertension 1991 Mar
PMID:High NaCl diet enhances arterial baroreceptor reflex in NaCl-sensitive spontaneously hypertensive rats. 199 66

The results of 8 to 12 weeks of treatment of the anemia of uremia with rHuEPO in patients with chronic renal failure and uremia are: a sustained increased hematocrit; increased RBC mass, and subsequent increased MAP; and increased TPRI. The observed trends of decreased LVEF, and echo Doppler evidence of a trend toward LV systolic and diastolic dysfunction, although not individually statistically significant, represent 3 separate evaluation techniques coupled with hypertension and TPRI increase during administration of rHuEPO to increase the hematocrit and packed red blood cell volume in patients with chronic renal failure and anemia. Increased TPRI and hypertension associated with correction of uremic anemia vasodilation and the increased blood viscosity have been noted in earlier investigations with transfusions. The hypertension and elevated TPRI demonstrated during rHuEPO therapy in patients with progressive chronic renal failure associated with increased hematocrit, and the trends toward systolic and diastolic cardiac dysfunction are noted herein. These changes were associated with the combined increase of packed RBC mass and plasma volume in this study. The natural progressive course of worsening of renal function exhibited by these patients could have limited their ability to regulate plasma volume, making them vulnerable to volume-dependent hypertension and a significant preload adding to potential cardiac dysfunction in addition to the increased TPRI.
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PMID:Cardiovascular hemodynamic effects of correction of anemia of chronic renal failure with recombinant-human erythropoietin. 205 68


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