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

Nitroglycerin improves perfusion to ischemic myocardial regions and therefore has theoretical advantages over sodium nitroprusside to treat hypertension (mean arterial pressure [MAP] greater than 95 mm Hg) following coronary bypass operation. Thirty-three hypertensive patients were randomized to an initial infusion of either nitroglycerin or nitroprusside in a crossover trial designed to reduce MAP to 85 mm Hg. Thermodilution cardiac output measurements permitted calculation of left ventricular stroke work index (LVSWI), and nuclear ventriculograms permitted estimation of left ventricular ejection fraction, left ventricular end-diastolic volume index (LVEDVI), and left ventricular end-systolic volume index (LVESVI). Coronary sinus blood flow was measured by the continuous thermodilution technique, and arterial and coronary sinus lactate measurements permitted calculation of myocardial lactate flux (MVL). Both nitroglycerin and nitroprusside reduced MAP (-25 +/- 12 mm Hg and -20 +/- 10 mm Hg, respectively; not significant [NS]). Nitroglycerin reduced LVSWI more than did nitroprusside (-15 +/- 13 gm-m/m2 and -7 +/- 9 gm-m/m2, respectively; p less than 0.01). Both agents increased left ventricular ejection fraction (nitroglycerin, +8 +/- 8%, and nitroprusside, +10 +/- 7%; NS), and decreased LVEDVI (-20 +/- 22 ml/m2 and -11 +/- 17 ml/m2, respectively; NS) and LVESVI (-13 +/- 14 ml/m2 and -10 +/- 12 ml/m2, respectively; NS). Coronary sinus blood flow decreased with both drugs (NS), but MVL increased with nitroglycerin (+0.02 +/- 0.14 mmol/min) and decreased with nitroprusside (-0.02 +/- 0.02 mmol/min) (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A comparison of nitroglycerin and nitroprusside: I. Treatment of postoperative hypertension. 391 59

The present study was undertaken to study the changes in efferent renal sympathetic nerve activity (RSNA) and heart rate (HR) during the acute fall in blood pressure after surgical reversal of two-kidney, one-clip renovascular hypertension in rats, and to explore if cardiopulmonary vagal afferents can influence sympathetic outflow in this situation. In 14 rats with a MAP of 199 +/- 6 mmHg the renal artery clip was surgically removed and after 90 min MAP had decreased to 109 +/- 7 mmHg. The HR had then decreased by 26 +/- 15 beats min-1 (P less than 0.05) and RSNA did not increase as expected, but was somewhat reduced (84 +/- 8% of control). In contrast, lowering pressure with nitroprusside to the same extent produced large and significant increases in HR and RSNA in seven other renal hypertensive rats. Acute bilateral vagotomy was performed in seven of the declipped rats, which induced an immediate increase in MAP (+35 +/- 10 mmHg, P less than 0.05), HR +28 +/- 10 beats min-1, P less than 0.05) and RSNA (+51 +/- 19%, P less than 0.05). A few minutes afterwards the vagotomy pressure again started to fall and was, after another 90 min 107 +/- 10 mmHg together with slight reductions in HR and RSNA. Another group of six rats were initially exposed to bilateral vagotomy. In these vagotomized rats declipping also induced hypotension (204 +/- 10 to 95 +/- 7 mmHg, P less than 0.001), together with tendencies of decreases in HR (425 +/- 17 to 397 +/- 17 beats min-1) and in RSNA (-4 +/- 6%).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Sympathetic inhibition after surgical reversal of renovascular hypertension in rats. Role of vagal nerves. 396 86

The media cross-sectional area, the media thickness, the internal radius and the ratio between media thickness and internal radius were determined in consecutive sections of extraparenchymal cerebral arteries of 7- and 12-month-old normotensive and spontaneously hypertensive rats. The study included intracranial pial and basal arteries as well as extracranial cervical arteries. In the chronically hypertensive rats the media to radius ratio was consistently higher than in normotensive rats over the entire calibre spectrum investigated (radius 5-400 micron). The increase of the ratio in the extracranial arteries of the hypertensive rats was exclusively due to a thicker media. In the basal intracranial arteries the increase of ratio was due to a thicker media and/or a smaller internal radius in 7- and 12-month-old rats with moderate hypertension (mean arterial pressure, MAP 171 +/- 8 and 177 +/- 7 mm Hg respectively). In 7-month-old rats with severe hypertension (MAP 204 +/- 11 mm Hg) the increase of ratio was mainly due to a smaller internal radius. The observed structural alterations are likely to be of hemodynamic importance.
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PMID:The morphometry of consecutive segments in cerebral arteries of normotensive and spontaneously hypertensive rats. 397 70

This discussion identifies the risks and benefits of each of the hormonal methods of contraception -- combined estrogen-progesterone oral contraceptive (OCs), progestogen-only pills, and depot progestogen injections. It also explains the use of a profile of risk factors in considering the appropriate prescription for each individual in relation to her contraceptive needs. Information regarding medical risks has come from the consideration of mortality rates in large cohort studies. Looking at categories of the causes of 249 deaths in ever-users of the pill and controls, Layde and colleagues were able to show that there was an excess mortality in the pill group of 40% and that the extra risk was concentrated in cardiovascular causes: myocardial infarctions, cerebral thrombosis, and cerebral hemorrhage constituted the largest proportions. A small proportion of combined OC users may develop clinical hypertension but more suffer a reduction in the high-density lipoprotein (HDL) cholesterol fraction of the blood lipids. Both of these effects tend to increase the risk of cardiovascular complications and both are positively related to the dose of the progestogen components. In prescribing combined OCs, attention needs to be paid to further moves away from the norm towards the extremes: the presence of cardiovascular risk factors and the use of certain longterm medications or the presumptive designation as a "rapid metabolizer." An analysis of progestogen only pill (POP) users in the Oxford-Family Planning Association study confirmed the reasonably low rates of accidental pregnancy in POP users. There is a marked reduction with increasing age, and it is significant that many prescribers are now giving POP to older women for whom combined OCs are contraindicated because of cardiovascular risks. It also seems reasonable to use them in women with some medical disorders, for example, recurrent pulmonary embolism, hypertension, and diabetes. Initially, depot injections of progesterone were developed to provide a long-acting or sustained-release type of drug administration to assist users of the progestogen-only method which, unlike combined OCs, does not make use of regular drug-free intervals. In practice it has been found that the effectiveness against pregnancy is enhanced and the side-effects are increased in giving progestogen by depot injection. The 2 preparations currently licensed in Britain are Depo-Provera (medroxyprogesterone acetate) and Noristerat (norethisterone enanthate). In some cases proper and clear information may not have been given to the patient and proper consent not obtained before giving the drug. This problem is magnified because of the occurrence in some women of disturbed bleeding patterns, especially if given immediately after childbirth or an abortion. Also, in a small proportion of users anovulatory amenorrhea may supervene for some months or even as long as 2 years following depot injection.
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PMID:Hormonal contraceptive methods. 401 68

Drug companies have been at work throughout the 1960s, 1970s, and 1980s trying to reduce the steroid content of their oral contraceptives (OCs). Researchers have been successful in reducing steroid content while maintaining effectiveness, thereby making OCs safer. In the 1st half of the natural menstrual cycle, a woman secretes estrogen as the dominant steroid product. In the 2nd half, estrogen is the principal reproductive hormone. Estrogens inhibit ovulation, possibly by inhibiting implantation, altering ovum transplant, or in some way preventing corpus luteum function, which is necessary to maintain early pregnancies and the endometrium. There are still only 2 estrogens and 6 progestins on the market today. They are probably the most thoroughly studied chemical ever seen in the history of pharmacy or medicine. 1 of the estrogens, mestranol, is really a drug of the past. In the body, mestranol is converted to ethinyl estradiol, the other estrogen on the market. Consequently, there is no reason to use mestranol itself. Within the dose range of 50-100 mcg, there's little difference in contraceptive effect. Progestins are the other active ingredient in the combination OC. Their principal action is the thickening of the cervical mucus, which prevents sperm penetration. Also, with sufficient progesterone, ovulation is inhibited, but this happens in only 40% of those patients taking, for instance, the "mini-pill" (which consists of progesterone only). The progestins and the estrogens work in concert to make OCs a highly effective contraceptive method. Recent surveys conducted by the Centers for Disease Control and National Cancer Institute looked into the relative effectiveness of OCs. Nordette had a use effectiveness failure rate of 3.5; Ovral, 3.6. Loestrin 1/20 -- norethindrone acetate, 1 mg, and estinyl estradiol, 20 mcg -- shows a failure rate of 4.5. This indicates that the threshold for an effective dose of estinyl estradiol in OCs is 30 mcg. For 1 mini-pill, Ovrette, the failure rate is 9.5 -- much higher. Depo-Provera has a failure rate of 0.7. The primary complaint from women taking OCs is spotting and breakthrough bleeding during the cycle. 30-50% of women given OCs stop taking them within a year. OC side effects include nausea, fluid retention, breast tenderness, leukorrhea, hypomenorrhea, headaches, spotting around the face, hypertension, and visual changes. 1 of the risks of birth control pills may be cervical dysplasia -- changes in the cells of the cervix. The relative risk of cervical cancer with OCs after 5-9 years is approximately 1.8. Clinical cases of deep vein thrombosis number 1/1000 per year among nonusers of OCs. Among users, the rate is 3 times as high: 3/1000. The most serious potential adverse effect is myocardial infarction. Of the excess deaths attributed to OCs (23.3 total per 100,000 users), 22.7 are due to myocardial infarctions and hemorrhage. The discussion also briefly reviews other methods of contraception -- Depo-Provera, male contraceptives, implants, the diapragm, and IUDs.
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PMID:Prescription contraceptives: countering the risks. 405 Jun 70

Twelve males with moderately severe essential hypertension (mean arterial pressure [MAP] ranging 113-162 mmHg) were studied at rest supine and sitting and during bicycle exercise (50, 100 and 150 W). Intraarterial blood pressure (BP), and heart rate (HR) were recorded continuously. Cardiac output (CO) was measured by dye dilution (Cardiogreen). After 6-8 months (enalapril dose 10-40 mg daily) patients were restudied. BP fell in all patients, at rest sitting from 184/107 mmHg to 150/87 (-19%) and during 100 W from 223/117 to 194/98 mmHg (p less than 0.001). Pretreatment total peripheral resistance index (TPRI) was greatly increased in all patients and fell from 4137 to 3651 dyn s cm-5 m2 (-16%) (p less than 0.05). No significant changes were seen in CO, HR or stroke volume. No side effects were seen. It is concluded that enalapril reduces BP in patients with moderately severe hypertension at rest and during exercise due to reduction in TPRI without significant changes in CO or HR.
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PMID:Long-term haemodynamic effects of enalapril at rest and during exercise in essential hypertension. 608 23

A follow-up study was conducted with 50 healthy parous volunteer women in India to ascertain the effect of a long-acting progestogen contraceptive on serum enzymes and hepatic function. The women received an intramuscular injection of a long-acting contraceptive, DMPA (depo-medroxyprogesterone acetate), in a dose of 150 mg every 3 months for 2 years. Women with a past history of jaundice, diabetes, hypertension, or eclampsia were excluded from the study. The activity of SGOT, SGPT, and AP (alkaline phosphatase) did not show any change during the longterm treatment. This result would indicate normal hepatic function and the absence of any damage or injury to the liver cells. Activity of serum ACP (acid phosphatase) and AChE (acetylcholinesterase) in red cells did show significant increase, which continued up to the end of the study. Results of the study indicate that DMPA is a suitable contraceptive for use in India, particularly since it does not cause the common side effects associated with oral contraceptives and does not affect liver function.
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PMID:Effect of medroxyprogesterone acetate contraception on human serum enzymes. 611 6

Twenty-two patients, aged 33-72 years, with uncomplicated essential hypertension were given sequential incremental intravenous infusions of sodium nitroprusside, each of 10 min duration, to examine the determinants of the vasodepressor response. Changes in mean arterial pressure (delta MAP), heart rate (delta HR), and plasma norepinephrine (delta nc) were determined at the end of each infusion period. The slopes of the dose-response curves obtained were directly proportional to predrug blood pressure (p less than 0.0001) and inversely proportional to baroreflex sensitivity as measured by the slope of the delta HR vs. delta MAP relationship (p = 0.0007). Baroreflex sensitivity was in turn inversely proportional to, and approximately equally dependent on, predrug blood pressure and age (p = 0.0116). Thus, the slopes of the dose-response curves were determined by both predrug blood pressure and patient age. The relationship was such that predrug blood pressure accounted for approximately 75% of the variability in the slope of the dose-response curve, and age for only 25%. This suggests that the age-related reduction in baroreflex sensitivity is mechanistically different from the hypertension-related reduction and is of less importance in modifying homeostatic responses to vasodilation.
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PMID:Age and blood pressure determine vasodepressor response to sodium nitroprusside. 620 85

The relationship between left ventricle-to-body weight ratio (LV/BW), mean arterial pressure (MAP, the average of 12 h of intra-arterial monitoring in conscious animals) and plasma renin activity (PRA) was assessed at 12 weeks after unilateral clipping or sham operation in twenty-four one-kidney rats and twenty-six two-kidney rats. The degree of hypertension and left ventricular hypertrophy were similar in one-kidney and two-kidney groups. There was a close linear relationship between LV/BW and MAP which was similar in one-kidney and two-kidney rats. PRA was significantly elevated only in two-kidney rats and was not related to the degree of hypertrophy after accounting for the effect of PRA on MAP. These data suggest that activation of the renin-angiotensin system does not contribute directly to myocardial hypertrophy in rats with renal-clip hypertension.
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PMID:The renin-angiotensin system and hypertensive left ventricular hypertrophy in the rat. 624 Mar 58

Trophic adrenergic influences may in part potentiate the pressure dependent development of structural cardiovascular changes in hypertension. Regression of such changes by antihypertensive treatment should therefore be most successful if adrenergic blocking drugs are used. In the present study spontaneously hypertensive rats (SHR) received either alpha-methyldopa, metoprolol, felodipine, a new vasodilating Ca2+-antagonist, or metoprolol and felodipine in combination for 10 weeks. Their left ventricles were weighed and resistance vessel design was analysed using a haemodynamic technique. Arterial pressure (MAP) was equally reduced by metoprolol and felodipine. Despite their different modes of action cardiovascular design was also equally affected. The combined regimen reduced average MAP more than either drug alone. It also caused more pronounced regression of cardiovascular structural changes. Methyldopa lowered MAP less than either metoprolol or felodipine and had only modest effects on cardiovascular design. Thus, the extent of MAP reduction, regardless of which therapeutic regimen is used to induce it, determines the extent of regression of structural cardiovascular changes during antihypertensive treatment.
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PMID:Regression of structural cardiovascular changes by antihypertensive therapy in spontaneously hypertensive rats. 624 24


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