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

ACEIs, angiotensin II receptor antagonists, and calcium antagonists are effective and well-tolerated antihypertensive agents but, except in special situations, should be considered alternative drugs for first line therapy until randomized trials show that they are at least as effective as diuretics and beta-blockers in preventing cardiovascular morbidity and mortality for a broad spectrum of hypertensive patients. ACEIs are particularly indicated for managing patients with congestive heart failure due to systolic dysfunction and patients with diabetic nephropathy, especially in Type I diabetes. Theoretically, the AII receptor antagonists will be equally effective for these indications, and randomized trials are now underway to demonstrate this. Special indications for calcium antagonists in the management of hypertension include angina pectoris, and for the non-dihydropyridine calcium antagonists, paroxysmal supraventricular tachycardia, and atrial fibrillation with rapid ventricular rate. Isolated systolic hypertension in the elderly is a special indication for long-acting dihydropyridine calcium antagonists, although diuretics are preferred. Calcium antagonists have been particularly effective in managing hypertension induced by cyclosporine. They are contraindicated in CHF due to systolic dysfunction and in the management of acute myocardial infarction. The long-term cardioprotective effect of calcium antagonists after a myocardial infarction has been demonstrated only for verapamil and diltiazem in patients with no evidence of LV dysfunction during their infarction. Calcium antagonists should be prescribed for this purpose only when beta-blockers are poorly-tolerated or contraindicated.
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PMID:Antihypertensive therapy. Angiotensin-converting enzyme inhibitors, angiotensin II receptor antagonists, and calcium antagonists. 935 1

1. The effects of combined inhibition of neutral endopeptidase 24.11 and angiotensin-converting enzyme, with the dual metallopeptidase inhibitor, MDL 100,240 (3 mg kg-1 bolus, 3 mg kg-1, h-1 infusion), on baseline haemodynamics and on responses to a variety of vasoactive peptides were studied in conscious Long Evans rats (350-450 g: n = 9) chronically instrumented for the assessment of regional haemodynamics. 2. The experiments ran over 4 consecutive days. On the first 2 days the animals received the vehicle for MDL 100,240, and were given bolus i.v. injections of angiotensin I (AI; 250 pmol kg-1), angiotensin II (AII; 125 pmol kg-1), bradykinin (BK: 3 nmol kg-1) and endothelin-1 (ET-1; 250 pmol kg-1) on one day and AI (as above), atrial natriuretic peptide (ANP: 500 pmol kg-1) and big endothelin-1 (big ET-1; 500 pmol kg-1) on the other day in a random manner. On the third and fourth experimental days the vasoactive peptides were given in the same order as before, but in the presence of MDL 100,240. 3. Thirty minutes after onset of administration of vehicle, on the first or second experimental day, there were no consistent cardiovascular changes. However, at the same time following onset of MDL 100,240 administration on the third experimental day, there was a significant, but slight, reduction in mean arterial blood pressure (MAP; -5 +/- 2 mmHg) together with tachycardia (41 +/- 12 beats min-1) and increases in renal and mesenteric flows (17 +/- 3 and 13 +/- 4%, respectively) and vascular conductances (23 +/- 4 and 19 +/- 5%, respectively). The mesenteric vasodilator effect of MDL 100,240 was still present on the fourth experimental day before administration of the drug on that day, but otherwise the pattern of response to MDL 100,240 was similar to that on the previous day. 4. In the presence of vehicle, AI caused hypertension, bradycardia, and reductions in renal mesenteric and hindquarters vascular conductances; all these effects were abolished by MDL 100,240. 5. In the presence of vehicle, AII caused effects similar to those of AI. MDL 100,240 did not affect the pressor, bradycardic or hindquarters vasoconstrictor effects of AII. However, in the presence of MDL 100,240, the overall renal and mesenteric vasoconstrictor effects of AII were enhanced, probably because of the renal and mesenteric vasodilatation caused by MDL 100,240. 6. In the presence of vehicle, BK had a slight pressor effect, accompanied by tachycardia and transient increases in conductances in renal, mesenteric and hindquarters vascular beds. In the presence of MDL 100,240 BK caused marked hypotension, but an attenuated tachycardia; renal, mesenteric and hindquarters vasodilator responses were enhanced. 7. In the presence of vehicle, ANP caused slight hypotension and tachycardia, together with reductions in renal and mesenteric vascular conductances, and transient increases in hindquarters conductance. MDL 100,240 enhanced the hypotensive effect of ANP and promoted a delayed hindquarters vasoconstriction. 8. Big ET-1, in the presence of vehicle, caused a marked and prolonged increase in MAP, accompanied by bradycardia and reductions in renal, mesenteric and hindquarters vascular conductances. Although MDL 100,240 significantly attenuated the magnitude of the pressor effect of big ET-1, its bradycardic and renal, mesenteric and hindquarters haemodynamic actions were not reduced significantly. 9. In the presence of vehicle, ET-1 caused an initial hypotension, tachycardia and vasodilatation in the hindquarters, but reductions in renal and mesenteric vascular conductances; thereafter there was a rise in MAP and bradycardia with vasoconstriction in all three vascular beds. MDL 100,240 had no effect on the initial hypotensive, tachycardic or hindquarters haemodynamic effects of ET-1. Moreover the subsequent pressor and bradycardic actions of ET-1 were unchanged, but its renal and mesenteric vasoconstrictor effects were enhanced, possibly because of the dilatation
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PMID:Effects of the dual metallopeptidase inhibitor, MDL 100,240, on regional haemodynamic responses to vasoactive peptides in conscious rats. 942 15

This study is the first approach to evaluate whether human atrial natriuretic peptide (hANP) is involved in the pathophysiology in transient puerperal hypertension (TPH). Five women who were normotensive throughout pregnancy, labor, and delivery developed hypertension between the first and sixth postpartum day. hANP (pg/ml) and plasma renin activity (PRA, ng/ml/h), angiotensin I, II (AI, II, pg/ml), and aldosterone (Aldo, pg/ml) in plasma were quantified by radioimmunoassay. Ten women without hypertension were also studied on hANP, PRA, AI, AII, and Aldo sequentially as the control group. hANP was apparently lower in women with TPH than in normotensive women. The levels of PRA, AI, AII, and Aldo were also clearly decreased in women with TPH, whereas those values in normotensive women were not altered from nonpregnant levels. Maternal natriuresis usually reaches the peak at 3-5 days postpartum. The decrease of hANP and PPA, AI, AII, and Aldo in TPH coincides with this natriuretic period. This observation suggests that hANP may serve an important role in the pathogenesis of TPH.
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PMID:Atrial natriuretic peptide in transient puerperal hypertension. 943 15

We studied the effect of the combination of streptozotocin-induced diabetes and spontaneous renal injury in male MWF rats. Renal hemodynamics was studied by micropuncture 1 month after streptozotocin administration, and kidney morphological evaluation was performed after 4 months of diabetes. We also studied the effect of angiotensin II antagonism on development of renal lesions. Untreated animals developed mild hypertension, proteinuria, and glomerulosclerosis. Induction of diabetes, and maintenance of a moderate hyperglycemic state, was associated with slight but significant elevation in systemic and glomerular capillary blood pressure. Development of proteinuria was not accelerated or exacerbated by diabetes. Glomerular and tubular structural changes were also not worsened by diabetes. Antihypertensive treatment with an ACE inhibitor (benazepril) or with an AII receptor antagonist (valsartan) almost completely prevented systemic and glomerular capillary hypertension, proteinuria and renal structural changes. No significant differences in glomerular volume were observed among the four groups. That induction of experimental diabetes, although associated with glomerular capillary hypertension, did not aggravate the rate of progression of renal dysfunction would suggest that glomerular injury is not directly influenced by glomerular hemodynamic conditions in these animals. Prevention of renal functional and structural abnormalities by antagonism of AII activity in diabetic MWF rats suggests a pathogenetic role for angiotensin in inducing the renal disease in these animals.
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PMID:Prevention of renal injury in diabetic MWF rats by angiotensin II antagonism. 952 71

This study shows the development of two major deformities in the non-stenosed kidney of the 2K-1C Goldblatt model; namely the widening of the LIS and the enlargement of the basilar interdigitations of the proximal tubule cells. These deformities were much less in the 2K-1C animals treated with the angiotensin I converting enzyme inhibitor (AICEI) cilazapril. From these findings it is suggested that the non-stenosed kidney is operating under the diuretic effect of the elevated systemic blood pressure (SBP) via an increase in the renal interstitial hydrostatic pressure (RIHP). Therefore, the AII antidiuretic effect is masked by the diuretic effect of the elevated SBP. The suggested rise in urine output fits well with the idea that kidneys lose water and sodium when SBP increases enormously. Therefore, in this model of hypertension, the non-stenosed kidney tries to lower SBP by losing water and sodium, an excretion behavior which is opposite to that of the stenosed kidney. Thus, the rise in SBP in this model is probably due to an increase in the vascular peripheral resistance rather than fluid accumulation.
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PMID:Distention of the lateral intercellular spaces (LIS) in the proximal tubule cells of the non-stenosed kidney of the 2K-1C Goldblatt model of hypertension as evidence of pressure diuresis. 965 49

We hypothesized that hyperinsulinemia may alter insulin's ability to stimulate vascular Na+/K(+)-ATPase pump activity and modulate changes in vascular responsiveness associated with hypertension. We measured potassium-induced relaxation as an indicator of Na+/K(+)-ATPase pump activity in isolated femoral arteries from fructose-fed (FF) hyperinsulinemic, Sprague-Dawley rats. FF rats had higher mean arterial blood pressures than did normal diet-fed (NF) rats (FF, 125 +/- 2.2, n = 20, vs. NF, 113.5 +/- 2.5 mmHg, n = 20, p < 0.05) and were hyperinsulinemic (FF, 64 +/- 4 vs. NF, 37 +/- 2, microU/ml insulin, p < 0.01). FF rats were more sensitive to KCl in the Na+/K+ pump bioassay (FF, 0.86 +/- 0.07, n = 21 vs. NF, 1.18 +/- 0.08, n = 17, p < 0.05, expressed as ED50 in mmol/l KCl). Exogenous insulin (100 mU/ml) increased Na+/K+ pump sensitivity in FF rats as compared with a boiled insulin control (insulin 45 +/- 6%, n = 11, vs. control, 11 +/- 7%, n = 13, p < 0.01, expressed as percent increase in sensitivity, i.e., ED50). There were no significant differences in Na+/K+ pump sensitivity between insulin and control responses in the NF animals (insulin 29 +/- 6%, n = 11, vs. control 46 +/- 5%, n = 10, NS). Dose-response curves were obtained in tail and femoral arteries from the same animals to norepinephrine and acetylcholine, basally and after exogenous insulin. FF vessels had reduced sensitivity to norepinephrine as compared with the NF group. Insulin increased sensitivity to acetylcholine-induced relaxations and increased AII-induced contractions in FF-rat vessels. These data suggest that in the FF rat insulin's influence on the vascular Na+/K+ pump is enhanced and may modulate the changes in vascular responsiveness seen in this model.
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PMID:Increased functional Na(+)-K+ pump activity in the vasculature of fructose-fed hyperinsulinemic and hypertensive rats. 966 2

Recently, several antagonists of angiotensin II receptors (AII-A) have been developed and are now used as antihypertensive agents. The regional cerebral blood flow appears to show typical changes during the course of cerebral ischemia and AII-A may have a favorable effect on the flow in some situations. Moreover, activation of the renin-angiotensin system plays an important role in the development of cerebrovascular lesions in chronic hypertension. Because several enzymes appear to produce angiotensin II in the absence of classical renin-angiotensin system, it is possible that angiotensin II is produced in some blood vessels even after inhibition of the activity of ACE. Thus, AII-A may be more effective to treat cerebrovascular lesions during hypertension than ACE inhibitors.
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PMID:[Angiotensin II receptor antagonists as the agents to treat cerebrovascular disease]. 1041 76

This study was to assess the role of different components of the extracellular matrix (ECM) on the mobilization of Cai++ induced by angiotensin II in vascular smooth muscle cells (VSMC) from hypertensive (SHR) and normotensive (WKY) rats. The effect of AII (10-6 M) on Cai++ release was studied in VSMC isolated from the aorta of 5-week-old WKY and SHR using fluorescent imaging microscopy (fura-2). Cai++ mobilization was characterized by amplitude, slope of Cai++ increase and total amount of Cai++. Cells were cultured on glass coverslips (control) or coated with either collagen I, collagen IV, vitronectin, fibronectin and extracellular matrix (ECM) and studied at confluence between passage 3 and 9. A significant increase of Cai++ released by AII has been observed with cells from WKY cultured on collagen I (meam +/- SEM, amplitude: 192 +/- 12% of control values, slope: 194 +/- 13%, total amount Cai++: 173 +/- 12%, n = 270, p < or = 0.0001 for each, unpaired t-test). Conversely, response with SHR was not significatively modified. Cai++ mobilization was not significatively modified after culture of VSMC from SHR and WKY on collagen IV. A significative decrease of the slope (WKY: 66 +/- 6%, p < or = 0.0001; SHR: 83 +/- 5%, p < or = 0.03) and of the amount of Cai++ (WKY: 74 +/- 7%, p < or = 0.01; SHR: 74 +/- 5%, p < or = 0.01) has been observed after culture of VSMC from the 2 strains on vitronectin. A decrease in amplitude (53 +/- 3%, p < or = 0.0001), slope (38 +/- 4%, p < or = 0.0001) and Cai++ release (69 +/- 5%, p < or = 0.004, n = 106) has been observed in VSMC from SHR seeded on fibronectin. Conversely, in VSMC from WKY, Cai++ mobilisation has not been modified compared with control cells. Culture of VSMC from SHR on ECM induced a significative decrease of amplitude (49 +/- 2%), slope (54 +/- 4%) and Cai++ release (53 +/- 3%, p < or = 0.0001 for each, n = 122), while in WKY, ECM induced a significative stimulation of these parameters (amplitude: 157 +/- 11%, slope: 149 +/- 13% and Cai++ release: 130 +/- 9%, p < or = 0.0001 for each, n = 247). These results show that the Cai++ mobilization induced by AII is modified by the adhesion of cells to different ECM components. This suggests a modulation of the A II-associated signalling events via the focal adhesion points. Furthermore, a difference in this modulation is observed between SHR and WKY when cells are seeded on collagen I, fibronectin or ECM. These modulations of Cai++ mobilization could play a role in the regulation of growth and differentiation of cells during the development of hypertension.
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PMID:[Cellular adhesion to elements of the extracellular matrix in the hypertensive rat modulates the effect of angiotensin II]. 1048 64

A large number of compounds known as "AII (Angiotensin II) antagonists" have been developed for the treatment of various heart diseases such as hypertension, congestive heart failure, and chronic renal failure. Most of the currently known AII receptor antagonists share a similar chemical structure, consisting of nitrogen atoms, a lipophilic alkyl side chain and an acidic group. As a new series, we have designed and synthesized various pyridylimidazole derivatives. In this report we would like to discuss the structure-activity relationship of these series of compounds using the comparative molecular field analysis (CoMFA) methods. We could come up with a good CoMFA model (cross-validated and conventional r2 values equal to 0.702 and 0.991, respectively) and the validity of the model was confirmed by synthesizing and measuring their biological activity of additional 6 compounds suggested by the model. This result provides additional information on the structural requirement for structurally diverse group of AII receptor antagonists.
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PMID:A comparative molecular field analysis and molecular modelling studies on pyridylimidazole type of angiotensin II antagonists. 1065 3

Factors responsible for hypertension in the spontaneously hypertensive rat (SHR) remain under investigation. As in human pregnancy complicated by essential chronic hypertension, the hypertension of the pregnant SHR subsides and returns postpartum. Because corticosteroid excess can cause hypertension, we examined several aspects of adrenocortical activity as potentially affecting the reported blood pressure profiles of nonpregnant, term pregnant, and postpartum SHR, using normotensive Wistar-Kyoto (WKY) rats as controls. We found that corticosterone levels were comparable in nonpregnant SHR and WKY rats, and unaffected by pregnancy. No differences were detected postpartum. Although pregnancy was accompanied by significant increases in plasma aldosterone levels, no interbreed differences were observed, which remained the case postpartum. Single adrenal cell secretion of aldosterone and corticosterone, as detected by reverse hemolytic plaque assay, yielded similar results in the pregnant and postpartum rat. Hormone responses to dietary manipulations in the nonpregnant and pregnant SHR and WKY suggest an important role for ACTH, and a lesser one for AII in the regulation of corticosteroids. In situ hybridization histochemistry, using a probe that detects both P450c11beta and P450c11AS mRNA, revealed comparable message density and zonal distribution in adrenals from pregnant and nonpregnant SHR and WKY rats. Breed- and pregnancy-dependent differences in adrenal expression of P450scc, P450c11beta, and P450c11AS were noted. In summary, our findings suggest that although some discrepancies exist in the aspects of adrenocortical activity examined, they are unlikely to be etiologic in the blood pressure profile observed in nonpregnant, pregnant, and postpartum SHR.
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PMID:Corticosteroid dynamics in the nonpregnant, pregnant, and postpartum spontaneously hypertensive rat. 1082 44


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