Family history and pathophysiological mechanisms of primary hypertension. Studies in non-hypertensive young men with positive and negative family histories of hypertension.

In an attempt to explore pathophysiological mechanisms relevant for the development for future primary hypertension, we investigated young normotensive men with positive family histories of hypertension (PFH) regarding blood pressure, body weight, systemic and renal haemodynamics as well as cardiovascular hormones and sodium homeostasis. Sixteen subjects with PFH and thirteen controls with negative family histories (NFH), matched for age and body weight were investigated at age 31 and after five years. Blood pressure and heart rate did not differ between the two groups at the first or follow-up examination. At follow-up body weight had increased and a positive correlation between blood pressure and body mass index was found in subjects with PFH, while subjects with NFH had unchanged blood pressure and body weight. Initially, intraerythrocyte sodium content was increased in subjects with PFH, however, at follow-up intraerythrocyte sodium content did not differ between the two groups. At follow-up systemic and renal haemodynamics and sodium homeostasis were investigated in fifteen subjects with PFH and in twenty-nine controls matched for age (36 +/- 5 year) and with NFH. The control group was divided into one group matched for body mass index (n = 15) and one group with normal body mass index (n = 14). Blood pressure and central venous pressure were measured during bolus injections of phenylephrine and during an acute saline/fluid load (1000ml 0.9% NaCl within 10 min). Renal haemodynamics and blood pressure were measured during low doses (0.1 and 0.5 ng/min/kg) continuous infusions of angiotensin II (AII). At baseline blood pressure, body weight and sodium excretion were higher in subjects with PFH and matched controls as compared with lean controls. Calf and forearm haemodynamics (pletysmography), plasma catecholamines, plasma renin activity, angiotensin II, aldosterone, blood volume and erythrocyte sodium efflux rate constant did not differ between the three groups. Circulating atrial natriuretic peptide was higher in subjects with PFH than in the two control groups. In subjects with PFH there was a negative correlation between renal sodium excretion at baseline and the ouabain-sensitive sodium efflux rate constant. During the acute saline/fluid load central venous pressure and systolic blood pressure increased more and venous vascular compliance (ml/mmHg/kg) was reduced in PFH. Atrial natriuretic peptide release and renal sodium excretion were blunted during saline/fluid load in subjects with PFH as compared with the two control groups. Renal blood flow and renal vascular resistance did not differ at baseline. Glomerular filtration rate was somewhat higher in PFH.(ABSTRACT TRUNCATED AT 400 WORDS)