Hypertension in blacks is common, often severe, and largely unexplained. Recent studies have suggested that aldosterone secretion in blacks may be reduced, whereas older data demonstrate no racial differences in aldosterone excretion. We performed this study to examine adrenal responsiveness in black hypertensive patients under controlled metabolic conditions. Thirty-one black hypertensive patients and 7 black normotensive subjects were studied on intakes of 10 mmol/d sodium and 100 mmol/d potassium, with the renin-angiotensin-aldosterone system further stimulated by upright posture or infusion of angiotensin II (Ang II). Forty-six hypertensive and 14 normotensive whites underwent the same protocol as a comparison group. Hypertensive blacks and whites had similar mean basal plasma aldosterone levels on a low salt diet, lower in both groups than in normotensive subjects. '-4 In response to suggestions of an increased incidence of primary aldosteronism in blacks, 5 a comparative study found no difference in aldosterone excretion between black and white normotensive subjects or hypertensive patients. 6 Recently, a reduction in aldosterone secretion was documented in black children, with strong familial influences on the aldosterone excretion rate. 78 The following description results from a systematic assessment of adrenal responsiveness in blacks, using three stimuli known to increase aldosterone secretion: restriction of sodium intake, upright posture, and angiotensin II (Ang II) infusion. MethodsWe studied 31 black patients (14 men, 17 women) with hypertension and 7 black normotensive men. Race was determined by self-identification and supported by physical appearance. The term "black" is used instead of "African American" because not all of the patients were American. Forty-six white hypertensive patients, matched with the black patients for age, gender, and body mass index, served as the comparison group. Although this group consisted of proportionately fewer women (Table 1), the difference was not statistically significant (# 2 =1.26). Fourteen white normotensive men were also matched for comparative study.Hypertension was defined as a systolic blood pressure greater than 140 mm Hg and a diastolic blood pressure greater
Interpretation of renin-angiotensin blockade with angiotensin converting enzyme inhibitors is potentially confounded by their multiple effects. We used a selective renin inhibitor (enalkiren, A-64662) to explore the renal and endocrine effects of angiotensin II in healthy men. Each received 90-minute enalkiren infusions at 2-day intervals, on a low (10 mmol, 16 subjects) and high (200 mmol, 12 subjects) salt diet Plasma renin activity, immunoreactive plasma angiotensin II and aldosterone concentrations, inulin, and p-aminohippurate clearance were measured by standard methods. Plasma renin activity fell at 0.1 m^/kg, but the threshold for biologic effect was 256 jug/kg, where plasma immunoreactive angiotensin II and aldosterone concentration fell, and renal plasma flow rose (p<0.01). The maximal renal vascular response (+152±23 ml/min/1.73 m 2 ) occurred at 512 /ig/kg (/?<0.01). Diastolic and mean blood pressure fell modestly but significantly (p<0.05). Responses were limited on a high salt diet We confirm that conventional plasma renin activity measurement is misleading in humans receiving a renin inhibitor. The renal vascular response to renin inhibition in this study appeared to substantially exceed reported responses to angiotensin converting enzyme inhibition, perhaps reflecting a crucial and relatively inaccessible intrarenal locus. (Hypertension 1991;17:510-516) P harmacological interruption of the renin-angiotensin system has played a special role in attempts to define its role in normal physiology and in the pathogenesis of disease. The reason is fundamental. Ablation of the source of a hormone followed by replacement has been crucial to defining the hormone's contribution. 1 In the case of the renin-angiotensin system, where the kidney is not only the source of the hormone but also a determinant of sodium homeostasis, the value of the ablation experiment has been limited. Pharmacological interruption of this system, therefore, has essentially replaced ablation as a pivotal step.The most widely used agents, the angiotensin converting enzyme (ACE) inhibitors, block an enzyme that has multiple functions, including degradation of kinins and consequent prostaglandin forma-
Hawthorn is a small thorny tree with white flowers and red berries that grows in temperature zones. Extracts from the plant were used centuries ago by the Greek physician Dioscorides, are widely prescribed in modern-day Germany for angina and congestive heart failure, and are now emerging as sought-after treatment for high blood pressure in America. Hawthorn (Crataegus), while not as well known as garlic, is just one of dozens of herbs that patients seek or are already taking "on the side." According to a recent survey published in the Journal of the American Medical Association (JAMA), the number of Americans using alternative medical therapies continues its steady rise, reaching more than 42% in 1997 [1]. It is not surprising that almost two thirds of doctors recommend alternative therapies to their patients at least once. But the subset of doctors who report using alternative therapies themselves reaches a remarkable 50% [2].Economics are further proof. Americans spent more than $21 billion on these therapies in 1997, exceeding out-of-pocket spending for all hospitalizations. Hypertension is a common diagnosis for which nontraditional remedies are requested.The reality is thus an overlap between alternative and traditional medicine, a widespread coexistence that makes exposure to herbs a regular occurrence in clinical practice. The sites below are intended to point healthcare providers in the best direction when searching for reliable online information on herbal medicine. A focus on hawthorn through these sites illustrates the search.In 1998, Congress established the NCCAM at the National Institutes of Health. The NCCAM is an "advocate for quality science, rigorous and relevant research, and open and objective inquiry into which CAM practices work, which do not, and why. Its overriding mission is to give the American public reliable information about the safety and effectiveness of CAM practices." Before that time, the NCCAM was the Office of Alternative Medicine (OAM), established in 1992. Its expansion increased the center's ability to initiate and fund additional research projects and to provide more information to the public.Click on the "For consumers and practitioners" tab, and then on "Complementary and alternative medicine databases." Once inside the citation index, which consists of more than 175,000 bibliographic entries, you can perform a single term or Boolean search in seconds. Thirty-four records were revealed by searching "hawthorn," with titles like "Comparisons of pharmacological effect and LD50 among four kinds of Hawthorn fruit;" and "Some structural characteristics of hawthorn glycoflavonoids." Most were in foreign languages, however, and little was available in terms of abstracts. HerbMEd www.herbmed.orgThis interactive, electronic herbal database provides hyperlinked access to scientific data underlying the use of herbs for health. HerbMEd is a free service provided by the Alternative Medicine Foundation, Inc. Click on "Crataegus" to find six categories of information: evidence for activ...
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