Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Dihydralazine is frequently used in severe pregnancy induced hypertension (PIH). Little is known about its effect on the human uteroplacental circulation. In this study, Doppler ultrasound recordings were made from branches of the uterine artery in 5 women with PIH and blood pressure (BP) greater than or equal to 150/100 who received either 7.5 or 10 mg dihydralazine, as repeated intravenous doses of 2.5 mg, before obtaining near-normal/normal BP values. The measurements started 5-10 min prior to the injections and continued as undisrupted as possible during injections and the subsequent 30 min. When the reduction in BP was obtained, the median blood velocity was reduced by 23% (range 10-29%). A/B ratio was calculated at the same time as an indicator of peripheral vascular resistance. The ratio increased, compared with pre-experiment values, in 3 subjects (5, 26 and 31%) but decreased in 2 (4 and 6%). Maternal tachycardia was noted in all but one woman. Continuous fetal heart rate (FHR) recording showed no signs of fetal distress. The uteroplacental circulation does not seem to benefit from the vasodilatory effects of dihydralazine, the response to the decreased perfusion pressure being a reduction in blood velocity and unchanged peripheral resistance.
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PMID:The effect of dihydralazine on blood velocity in branches of the uterine artery in pregnancy induced hypertension. 252 Jul 81

Ten patients with gestational proteinuric hypertension were studied with a Swan-Ganz thermodilution haemodynamic catheter before, during and after plasma volume expansion. Five patients were treated with dihydralazine before volume expansion and five after volume expansion. Before treatment all patients had a low pulmonary capillary wedge pressure (PCWP), low cardiac index (CI) and high systemic vascular resistance (SVR). Following volume expansion the PCWP and CI increased, the SVR decreased but the blood pressure (BP) was unchanged. Administration of dihydralazine following volume expansion led to a decrease in PCWP, an increase in CI and a decrease in SVR and BP. Dihydralazine alone caused an increase in heart rate, PCWP, and CI, and a decrease in SVR and BP. Volume expansion, by increasing CI and decreasing SVR, may be of therapeutic benefit in the severely hypertensive pregnant patient with a low cardiac index.
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PMID:Haemodynamic changes in gestational proteinuric hypertension: the effects of rapid volume expansion and vasodilator therapy. 280 85

Dihydralazine is widely used for acute control of hypertension. In experimental studies it seems to dilate cerebral resistance vessels and increase intracranial pressure. However, the effect on cerebral blood flow (CBF) in man has been little studied. Measurements of CBF were performed with the i.v. xenon-133 technique in seven young, normotensive volunteers before and 15, 60 and 180 min after 6.25 mg i.v. dihydralazine, corresponding approximately to 0.1 mg kg-1 body weight. For comparison the CBF reactivity to inhalation of 5% CO2 in air was investigated. Dihydralazine increased CBF throughout the period of study, in median 16, 27 and 23% at the three periods of measurements, respectively. The arterial blood pressure remained unchanged, whereas heart rate increased significantly. During CO2 inhalation, CBF increased on average 29%. Thus, the cerebral vasodilation exerted by a small i.v. dose of dihydralazine was of the same order of magnitude as the effect of 5% CO2 inhalation. These results in normal subjects should be extrapolated to diseased persons only with extreme caution. Still, the very marked and long lasting vasodilation observed suggests that dihydralazine, from a theoretical point of view, in certain clinical situations may be harmful.
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PMID:Dihydralazine induces marked cerebral vasodilation in man. 311 65

Labetalol (Trandate; Allen & Hanburys), a combined alpha- and beta-adrenergic blocking agent, was compared with the more commonly used peripheral vasodilator, dihydrallazine (Nepresol; Ciba), each administered as an infusion, in the treatment of severe hypertension in 20 primigravidas at greater than or equal to 32 weeks' gestation. With the dosage regimen used in this study there was a tendency towards more effective blood pressure control with dihydrallazine. The pulse rate was unaffected by labetalol therapy and there were no harmful effects on the neonate or fetus directly attributable to either drug.
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PMID:Comparison of labetalol and dihydralazine in hypertensive emergencies of pregnancy. 355 Nov 27

34 eclamptic patients treated at Harare Maternity Hospital during 1982 were managed by the use of diazepam to control convulsions, Nepresol to control the hypertension and prompt delivery. The average dose of diazepam given prior to delivery was 45.8 mgs. 80% of Greater Harare Unit patients were delivered by emergency caesarean section. The maternal mortality rate was 4% and the perinatal mortality rate 12% for patients within the Greater Harare Unit. The major factor contributing to maternal mortality in the cases reviewed was lack of antenatal care, or lack of acceptance of antenatal advice. All pregnant patients must be encouraged to book for antenatal care. The perinatal mortality is higher for unbooked patients, and in those patients witha long 1st fit-delivery interval. Perinatal mortality is also related to gestational age at delivery, mortality being greater in those patients delivered before 34 weeks gestation. A reduction in perinatal mortality could be achieved by all patients booking for antenatal care, aiming for a short 1st fit-delivery interval, and providing expert neonatal care for the pre-term infant.
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PMID:Management and pregnancy outcome in eclampsia at Harare Maternity Hospital. 404 45

In the rat model of hypertension induced by a clip on the right renal artery, sparing the left kidney, we compared the efficacity and the endocrine, renal and cardiac effects of classical therapy (CT) of hypertension (Clonidine 0.2 mg/kg and Dihydralazine 15 mg/kg in 2 daily subcutaneous injections and Furosemide 30 mg/kg/day in the drinking water), with inhibition of the angiotensin converting enzyme with a new drug, the S-9490-3 (0.5 mg/kg in one daily administration). The untreated animals (HT: n = 12) had an average systolic blood pressure (SBP) of 215 +/- 32 mmHg. After 1 month' treatment, S-9490-3 (n = 13) lowers SBP to 144 +/- 32 mmHg compared to CT (n = 12) which lowered SBP to only 172 +/- 18 mmHg. The average plasma renin concentrations of the HT animals was four times the normal value (39 +/- 33 ng/ml/h) and both treatment regimes increased it further (S-9490-3: 129 +/- 65 ng/ml/h; CT: 97 +/- 73 ng/ml/h). Angiotensin levels fell in proportion to the increase in renin concentration. Plasma aldosterone was normalised by S-9490-3 (460 +/- 320 pg/ml) but remained as high after CT (850 +/- 650 pg/ml) as in the untreated HT animals (830 +/- 260 pg/ml). Despite the Furosemide, plasma volume increased significantly in the CT group.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Comparison of the cardiac, renal and endocrine effects of converting enzyme inhibition with those of a classical triple therapy in experimental renal hypertension]. 609 34

Antihypertensive vasodilators share the capability of producing vasodilation of arterioles. In addition, two of them, i.e. nitroprussiate and prazosine, also produce vasodilation of veinulae. Both of these agents cause a simultaneous decrease in pre-load and post-load, and may be used in heart failure. The effectiveness of vasodilators is offset by regulatory cardiac and/or renal mechanisms, and the association with a sympatholytic agent and/or a diuretic is generally needed. Consequently, vasodilators are usually the third step in the course of managing a hypertensive patient. Association with a betablocking agent is especially necessary in patients with coronary insufficiency, in order to prevent an increase in myocardial oxygen requirements and worsening of angina pectoris. Vasodilators are active within a fairly wide dosage range, making individualized dosages requisite. In treating hypertension by the oral route, daily doses above 200 mg for dihydralazine, 60 mg for minoxidil and 10 mg for prazosine are only exceptionnaly useful. In emergency treatment of hypertension, diazoxide and nitroprussiate can be used only in patients under continuous cardiovascular monitoring. Nitroprussiate must, in addition, be given through a controlled infusion device, but ensures more flexible and safer control of blood pressure. Dihydralazine may produce headache. This side effect occurs very early and is hardly compatible with continuation of treatment. Long term side effects are very uncommon or strictly biological for dosages below 200 mg/day. With currently used dosages (20 to 60 mg per day) minoxidil consistently produces hypertrichosis, outruling its protacted use in women.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Antihypertensive vasodilators]. 631 28

Since systolic pressure is governed by the rate of ventricular ejection and the rigidity of the aortic wall, antihypertensive agents may have different effects on systolic and diastolic pressure. Despite an adequate decrease in diastolic pressure, systolic pressure may remain elevated due to structural alterations of large arteries. In the present study, a procedure is described to distinguish the dilation of small and large arteries. The former is evaluated from the calculation of forearm resistance and the latter from the determination of the arterial diameter of the brachial artery, using a bidimensional pulsed Doppler system. Nitroglycerin dilates the brachial artery, with no change in forearm resistance. Dihydralazine reduces the diameter of the brachial artery but decreases forearm resistance. Only calcium and converting-enzyme inhibitors dilate both small and large arteries and cause an increase in brachial blood flow.
Hypertension
PMID:Peripheral large arteries and the response to antihypertensive treatment. 641 51

The cerebrovascular effects of graded, controlled dihydralazine-induced hypotension were studied in rats with renal hypertension (RHR) and spontaneous hypertension (SHR). Repeated measurements of cerebral blood flow (CBF) were made using the intraarterial 133Xenon injection technique in anaesthetised normocapnic animals. Dihydralazine was administered in single increasing i.v. doses (0.1 to 2 mg/kg), and CBF measured after each dose when a stable blood pressure had been reached. From a resting level of 145 +/- 7 mm Hg in RHR and 138 +/- 11 mm Hg in SHR, mean arterial pressure (MAP) fell stepwise to a minimum of around 50 mm Hg. CBF was preserved during dihydralazine induced hypotension, and remained at the resting level of 79 +/- 13 ml/100 g . min in RHR and 88 +/- 16 ml/100 g . min in SHR. Following 2 hours hypotension at the lowest pressure reached, the rats were sacrificed by perfusion fixation and the brains processed for light microscopy. Evidence of regional ischaemic brain damage was found in 4 of 11 animals: in 2 cases the damage appeared to be accentuated in the arterial boundary zones. Although the lower limit of CBF autoregulation in these rats is around 100 mm Hg during haemorrhagic hypotension, dihydralazine brought MAP to around 50 mm Hg without any concomitant fall in CBF. This was interpreted as being due to direct dilatation of cerebral resistance vessels. The combination of low pressure and direct dilatation may have resulted in uneven perfusion, thus accounting for the regional ischaemic lesions.
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PMID:Cerebral blood flow during dihydralazine-induced hypotension in hypertensive rats. 669 14

Dihydralazine, which is used in the treatment of hypertension, causes a long-lasting hypotensive action by a direct vasodilator effect on arteriolar smooth muscle. The present study was carried out to investigate the effect of a daily single injection of dihydralazine (20 mg/kg, s.c.) for 14 days on the tyrosine hydroxylase (TH) protein quantity in some catecholaminergic rat brainstem areas such as the dorsomedial medulla (DMM), the ventrolateral medulla (VLM) and the locus coeruleus (LC). This study demonstrates that the dihydralazine produced (1) an 85% increase in TH protein quantity exclusively in the rostral part of DMM, (2) a 58% increase of TH protein content exclusively in the rostral part of the LC, and (3) a 37% increase of the TH protein quantity in VLM catecholaminergic area. To determine whether the increase in TH protein quantity could be related to a change in norepinephrine (NE) content, the rate constant of disappearance (k) of NE was measured in the catecholaminergic regions of the same rats treated with dihydralazine. Our results show that dihydralazine causes an increase of the TH protein, in addition to an elevation of NE content, within the subpopulations of catecholaminergic structures. These data suggest a selective response of the TH regulation to dihydralazine within the rostral DMM area which receives barosensory inputs.
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PMID:Regional specificity of long-term regulation of tyrosine hydroxylase in some catecholaminergic rat brainstem areas. II. Effect of a chronic dihydralazine treatment. 810 Jan 76


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