The relationship between renal cortical volume and predisposition to hypertension.

It has been proposed that a reduction in the number of nephrons is a renal abnormality that plays an important role in the pathogenesis of essential hypertension. The objective of this study was to determine whether renal cortical volume, used as a measure of the number of nephrons, is lower in normotensive subjects with a familial predisposition to develop essential hypertension than in subjects who lack this predisposition. For this purpose, we measured renal cortical volume using electron beam computed tomography in 26 white offspring to two hypertensive parents (OHT; 14 women, 12 men) and 27 white offspring of two normotensive parents (ONT; 13 women, 14 men) who were stabilized on a high sodium diet for 3 days (200 mmol/day). In women, mean age was significantly greater in OHT than ONT (46.1 +/- 4.9 [standard deviation] v 41.8 +/- 5.1 years, respectively, P = .04)In men, means for age and weight were greater in OHT than ONT (age: 47.1 +/- 7.7 v 37.9 +/- 8.1 years, P < .01; weight: 90.2 +/- 10.7 v 81.1 +/- 9.4 kg, P = .03.) In women, mean total cortical volume did not differ significantly between OHT and ONT (156 +/- 33.3 v 166 +/- 30.9 cc, P = .80). After adjustment for interindividual differences in age, mean total cortical volume remained not significantly different in OHT than ONT (160 +/- 29.0 v 162 +/- 32.4 cc, P = .83). In men, mean total cortical volume was significantly greater in OHT than ONT (210 +/- 33.6 v 180 +/- 20.0 cc, P = .01). After adjustment for interindividual differences in age, mean total cortical volume remained significantly greater in OHT than ONT (207 +/- 33.2 v 182 +/- 19.8 cc, P = .02). After adjustment for interindividual differences in body weight, mean total cortical volume did not differ significantly between OHT and ONT (201 +/- 21.7 v 187 +/- 20. cc, P = .09). The results of this study do not support the hypothesis that a decrease in renal cortical volume, as a result of a decrease in number of nephrons, is a characteristic of white women or men with a familial predisposition to develop essential hypertension.

Reproducibility of human kidney perfusion and volume determinations with electron beam computed tomography.

RATIONALE AND OBJECTIVES: Alterations in whole kidney, cortical, and medullary perfusion and volume play a pivotal role in various physiologic and pathophysiologic processes. Electron-beam computed tomography (EBCT) provides accurate measurements of these traits in animals, but their reproducibility in humans has not been established. METHODS: Perfusion, volume, and flow measurements were obtained by EBCT in eight healthy human volunteers under controlled conditions on two consecutive days. RESULTS: Mean values for whole kidney, cortical, and medullary perfusion and volume obtained with EBCT were similar in scan 1 and scan 2 (P > 0.1), and correlated highly. Coefficients of variation for the repeated measurements usually were less than 10%. Values obtained for renal regional perfusion and volume agreed with previously reported values. CONCLUSIONS: Electron-beam computed tomography estimates of single whole kidney, cortical, and medullary perfusions and volumes are highly reproducible in normal humans, and may be useful to advance understanding of renal involvement in human disease.

Atrial natriuretic peptide and blood pressure in a population-based sample.

OBJECTIVE: To assess the relationship of plasma atrial natriuretic peptide (ANP) levels with blood pressure levels and the occurrence of hypertension in a large population-based sample. DESIGN: We performed a cross-sectional study of the relationship between ANP levels and blood pressure levels, diagnosis of hypertension, and family history of hypertension in Caucasians from Rochester, Minnesota. MATERIAL AND METHODS: Plasma ANP and blood pressure levels were measured in 1,338 Caucasian subjects who were members of 301 three-generation families from the population of Rochester. Hypertension was defined as systolic blood pressure of 140 mm Hg or more or diastolic blood pressure of 90 mm Hg or more. Each subject in the parental generation was categorized as having zero, one, or two parents with hypertension. Analyses were done separately for each generation and gender stratum. RESULTS: Within gender and generation strata, we noted no consistent pattern of positive or negative correlation of plasma ANP levels with systolic blood pressure, diastolic blood pressure, or heart rate. Within the grandparental generation, mean plasma ANP levels did not differ between those with normal blood pressure and those with hypertension. In the parental generation, mean plasma ANP levels did not differ between subjects with zero, one, or two parents with hypertension. CONCLUSION: In Caucasians, interindividual differences in plasma ANP levels are not associated with interindividual differences in blood pressure levels, the diagnosis of hypertension, or family history of hypertension.

Pacemaker-induced friction rub and apical thrill.

A patient with acute myocardial infarction developed a loud systolic sound and apical thrill. Doppler ultrasound excluded interventricular septal rupture and significant mitral or tricuspid regurgitation. Auscultatory abnormalities disappeared after removal of a temporary pacing electrode, suggesting that the friction it created with intracardiac structures was responsible for these findings.