Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0085580 (essential hypertension)
 14,686 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The antihypertensive effect of clonidine has been attributed to acute inhibition of sympathetic outflow from the central nervous system. This conclusion is derived from experiments with single doses of clonidine. The mechanism of the long-term blood pressure-lowering effect of clonidine has been less well characterized. Antihypertensive therapy may alter renal hemodynamics and these changes may ultimately affect systemic blood pressure. We studied the effect of long-term clonidine therapy on intrarenal hemodynamics, the renin-angiotensin system, and selected indices of sympathetic nervous system activity in 13 patients with essential hypertension to further elucidate its action. Long-term clonidine therapy resulted in decreased MAP and RVR associated with the suppression of supine but not upright PRA. RPF, RBF, FF, and WBV did not change. UKA, on index of the the putative vasodilating renal kallikrein-kinin system, was also not changed. Our findings suggest a role for PRA in modulating RVR during long-term clonidine therapy. This was associated with the reduction observed in MAP.
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PMID:Reduced renovascular resistance by clonidine. 49 99

The renal vasodilatating properties of tertatolol demonstrated in animals have been confirmed in man. In a first study [Paillard et al., 1986], tertatolol (T) 5 mg and propranolol (Pr) 160 mg (SR) were given orally for 15 days to 2 groups of 9 patients with essential hypertension. Glomerular filtration rate (GFR), measured by inulin clearance and renal plasma flow (RPF) measured by PAH clearance increased in T group (+8.9%, p = 0.038 and + 13.0%, p = 0.007, respectively) and decreased in Pr group (-2.8%, NS and -13.4%, p < 0.001, respectively). Two clinical pharmacology studies [Leeman et al., 1986; Nitenberg et al., 1990] have shown specific and selective effects of tertatolol on the renal vasculature. In 8 hypertensive patients with chronic renal failure, the effects of tertatolol 5 mg were evaluated before and after 3 months of treatment on GFR using inulin clearance, and RPF, using PAH clearance [Hannedouche et al., 1991]. After 3 months of treatment, GFR and effective RPF increased significantly by 10 and 13%, respectively, whereas RVR decreased by 16% and the filtration fraction was unchanged. In summary, tertatolol 5 mg, contrasting with other beta-blockers, possesses a selective effect on the renal circulation beneficial to hypertensive patients. The mechanisms of this renal vasodilatation are not fully understood but might involve renal 5-HT1A receptor stimulation.
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PMID:Overview of novel renal properties of tertatolol. 790 18

Barnidipine is a stereoselective single isomer formulation of a long-term acting dihydropyridine calcium antagonist (CaA). In anaesthetised animals, the antihypertensive response to barnidipine is accompanied by a diuretic effect. The aim of the present study was to examine whether barnidipine increased renal blood flow in a conscious animal model for essential hypertension. We compared the regional specific hemodynamic effects of barnidipine with those obtained with its racemic mixture and amlodipine. Male adult spontaneously hypertensive rats (SHR) were instrumented with Doppler flow probes and catheters to measure renal (RVR), mesenteric (MVR) and hindquarter (HQVR) vascular resistance changes. One week after surgery, barnidipine, its racemic mixture, and amlodipine were intravenously administered at three doses (n> or =10 per dose) causing comparable reductions in mean arterial pressure (MAP). At doses of 3, 10 and 30 microg/kg barnidipine reduced MAP (+/- SEM) by 8+/-2, 26+/-3 and 45+/-4 mmHg. Equipotent effects on MAP were achieved by the racemic mixture of barnidipine at 10, 30 and 100 microg/kg, and by amlodipine at doses of 100, 300 and 1000 microg/kg. Following the 3 microg/kg and 10 microg/kg dose, barnidipine reduced MVR (% +/- SEM) by 4+/-4 and 19+/-4, and RVR by 8+/-2 and 15+/-4, respectively. In contrast, HQVR remained unaltered. Similar data were obtained for the racemic mixture of barnidipine and for amlodipine, although for the latter the changes in RVR were half of those found after barnidipine. After the highest doses of barnidipine, its racemic mixture as well as amlodipine, HQVR fell more than 25% whereas RVR and MVR remained unaltered. Analysis of the dynamic response to the CaAs revealed that the reductions in vascular resistance were associated with decreased myogenic-like oscillations in blood flow. We conclude that, in conscious SHR, the single isomer barnidipine reduces MAP at doses which are three times lower than its racemic mixture and 30 times lower than amlodipine. In contrast to short-acting CaAs such as nifedipine and isradipine, which reduce mainly HQVR and do not reduce RVR (Nievelstein et al.; Eur J Pharmacol 113:187-198, 1985), the three long-term acting CaAs preferentially dilated the mesenteric and renal vascular bed. In view of the elevation of RVR in essential hypertension, the reduction of RVR may contribute to the long-term antihypertensive effects of barnidipine and amlodipine.
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PMID:Preferential renal and mesenteric vasodilation induced by barnidipine and amlodipine in spontaneously hypertensive rats. 1169 24