Indenolol, a beta-blocker with partial agonism at vascular beta-adrenoceptors

Intrinsic sympathomimetic activity may attenuate some effects caused by treatment with beta-adrenoceptor blockers. Indenolol is a nonselective beta-adrenoceptor antagonist whose sympathomimetic properties have been shown in vitro but not in human beings. We infused indenolol cumulatively (5, 15, and 50 micrograms/100 ml tissue per minute for 15 minutes each, preceded by an infusion of saline solution) into the brachial arteries of nine hypertensive patients. Forearm blood flow (venous plethysmography), mean arterial pressure, and heart rate were monitored. During infusion at 5 micrograms/100 ml tissue per minute, forearm blood flow did not change, but it did increase dose-dependently at the greater infusion rates. This action was determined to be mediated by beta-adrenoceptor stimulation because propranolol (10 micrograms/100 ml tissue per minute for 15 minutes), given before treatment and then concomitantly with indenolol, abolished it (n = 5). Indenolol vasodilated forearm arterioles and this effect was antagonized by beta-blockade, thus demonstrating vascular intrinsic sympathomimetic activity. This property may contribute to its therapeutic action in human beings.     

Microalbuminuria in hypertension

Microalbuminuria is a sensitive marker of early renal damage in essential hypertension as well as diabetes mellitus. Elevated urinary albumin excretion has positive correlations with other cardiovascular risk factors. Microalbuminuria has an independent value to predict cardiovascular disease in the patients with not only diabetes mellitus but also with essential hypertension and even in general population. The seventh report of the joint national committee on prevention, detection, evaluation and treatment of high blood pressure (JNC 7) has adopted microalbuminuria or estimated glomerular filtration rate < 60 ml/min as one of the major cardiovascular risk factors. It is an important future task whether decrease in urinary albumin excretion with treatment improves prognosis of individual patients.     

Hyperuricemia in hypertension

Hyperuricemia is one of the common complications in hypertension. The presence of hyperuricemia is closely correlated with the initiation of hypertension. In addition, the hypertension is known to increase the rate of hyperuricemia. Recently, it has been recognized that the hyperuricemia is one of the risk factors for cardiovascular events in hypertension. Therefore, the control of hyperuricemia might be critical for treatment of hypertension. Although the diuretics are important for the treatment of chronic heart failure and hypertension, it is reported to induce the hyperuricemia. Therefore, the careful and combination therapy for diuretics might be necessary to prevent the treatment-induced hyperuricemia. In the treatment of hypertension, especially with hyperuricemia, it might be important to select the drug, which does not influence or reduce the concentration of uric acid.     

Potassium in hypertension

Epidemiologic studies in the United States suggest that a low potassium intake may be important in the genesis of hypertension. The higher blood pressure in blacks than in whites in the United States is associated with lower excretion of potassium. This is probably due to less potassium being consumed. The high cost of a high-potassium diet may be the reason for the low potassium consumption. Potassium may reduce blood pressure by increasing sodium excretion, decreasing renin secretion, decreasing sympathetic nerve activity, or directly dilating the arteries.     

Pulmonary hypertension complicating portal hypertension: portopulmonary hypertension]

Portopulmonary hypertension is a condition with a poor prognosis, which is defined as precapillary pulmonary hypertension complicating portal hypertension mainly due to cirrhosis of various etiologies. A mean pulmonary arterial pressure greater than 25 mmHg at rest with a pulmonary capillary wedge pressure less than 15 mmHg and a pulmonary vascular resistance greater than 120 dynes.sec.cm-5, in the setting of the presence of portosystemic shunting has been proposed as hemodynamic criteria for portopulmonary hypertension. Prevalence of pulmonary hypertension ascertained by right cardiac catheterization was 2% among patients with cirrhosis, and reached to 4% particularly among candidates for liver transplantation. Hyperdynamic systemic circulation seen commonly in patients with cirrhosis appeared to be normalized by complication of pulmonary hypertension with a contraction of circulating plasma volume. Long term treatment by epoprostenol administration or nitric oxide inhalation could induce a gradual decline in pulmonary arterial pressure in patients with poor response to acute vasodilator administration.     

Mild hypertension in children

Essential hypertension (EHT) is found in 0.1 to 1% of Japanese school children. HT remains one of the major risk factors for the development of atherosclerosis and subsequent cardiovascular disease. EHT during childhood is usually mild, however, associated with end-organ damage such as left ventricular hypertrophy. In addition, it develops into adult hypertension. EHT is often seen in obese children. Furthermore, low birth weight has been reported to be closely associated with future EHT. Obese children are increasing and birth weight has a tendency of decreasing in Japan, it is, therefore, important to establish proper life-style from childhood throughout life.