The angiotensin converting enzyme and blood pressure in Jamaicans

An insertion/deletion (I/D) polymorphism of the angiotensin I converting enzyme gene influences the level of serum angiotensin converting enzyme activity and has been associated with risk of several cardiovascular conditions. The relationship to blood pressure remains uncertain, however. We conducted a population-based survey in Kingston, Jamaica, to examine the association between angiotensin converting enzyme genotype, angiotensin converting enzyme serum activity and blood pressure. Serum angiotensin converting enzyme activity was measured and genotyping performed for the I/D polymorphism in 500 community residents. The overall prevalence of the D allele was 59.3 percent. Angiotensin converting enzyme genotype was not significantly related to blood pressure (P - 16), although it did influence angiotensin-converting enzyme activity, leading to an increase of 35 percent among individuals with the DD as compared with II genotype. Angiotensin converting enzyme levels were significantly higher in hypertensives as compared with normotensives (P < .05). A modest correlation was observed between blood pressure and angiotensin converting enzyme activity among untreated individuals (r = 0.11; P = .04), although this did not persist in multivariate analysis. A relationship between body mass index and angiotensin converting enzyme activity was identified in both men and women that was independent of genotype. These data demonstrated findings among blacks which are consistent with other studies and suggest a relationship between angiotensin converting enzyme genotype, and serum activity which is influenced by both genetic and environmental factors. The potential role of ACE on blood pressure control in the population remains uncertain.(AU)

Clinical aspects of hypertension in Black Jamaicans

Hypertension is a major contributor to morbidity and mortality in the Caribbean today but data about this disease in the West Indies is scant and this thesis provides some of such much needed research information with particular emphasis on hypertension in blacks. A prospective analysis of admissions to the Medical Wards of the University Hospital of the West Indies during 1980 and 1981 describes the clinical features of black hypertensive patients. Most of these had developed complications within 10 years of the diagnosis of hypertension, and cardiomegaly, renal failure, cardiac failure and stroke were the commonest sequelae. Unlike the situation with white populations today, myocardial infarction was the least common of all the major complications seen in black Jamaicans. The present study was the first to document the renin profile of black Jamaicans and showed that 19 percent of hypertensives had high renin levels, 46 percent had normal levels and 35 percent had low renin levels, a pattern which was similar to that found in white populations. The infleunce of sickle cell anaemia, another common disease of blacks, on blood prressure measurements was assessed. The data showed that subjects with homozygous sickle cell disease may be protected against the development of hypertension since at every age the mean blood pressure was lower than in normal Jamaicans. In an attempt to rationalise drug therapy for hypertensives in the Caribean, earlier conclusions from Jamaica suggesting that beta-blockers may not be effective in blocks were re-examined in a double-blind trial. It was shown that hypertensive Jamaicans were sensitive to small doses of thiazide diuretics and may be less responsive than whites to conventional doses of beta-blockers, and that combination therapy produced a greater fall in blood pressure than either drug used alone. The thesis documented some of the clinical characteristics of the Jamaican hypertensive, provided data helpful for makin recommendations regarding the management of hypertension in the Caribean, and showed that racial factors may modify some of the manifestations of the disease.(AU)