Annexins are Ca2؉ -and phospholipid-binding proteins that are widely expressed in mammalian tissues and that bind to different cellular membranes. In recent years its role in membrane traffic has emerged as one of its predominant functions, but the regulation of its intracellular distribution still remains unclear. We demonstrated that annexin 6 translocates to the late endocytic compartment in low density lipoprotein-loaded CHO cells. This prompted us to investigate whether cholesterol, one of the major constituents of low density lipoprotein, could influence the membrane binding affinity and intracellular distribution of annexin 6. Treatment of crude membranes or early and late endosomal fractions with digitonin, a cholesterol-sequestering agent, displayed a strong reduction in the binding affinity of a novel EDTA-resistant and cholesterol-sensitive pool of annexin 6 proteins. In addition, U18666A-induced accumulation of cholesterol in the late endosomal compartment resulted in a significant increase of annexin 6 in these vesicles in vivo. This translocation/recruitment correlates with an increased membrane binding affinity of GST-annexin 6 to late endosomes of U18666A-treated cells in vitro. In conclusion, the present study shows that changes in the intracellular distribution and concentration of cholesterol in different subcellular compartments participate in the reorganization of intracellular pools of Ca 2؉ -dependent and -independent annexin 6.

Heart Station, Fall River General Hospilat, Fall River, MassachusettsThe fundamental cause of essential hypertension remains unknown, but adverse neurogenic control of vasomotor changes may be a predisposing factor in its maintenance. It has been established that hypertension is the result of increased resistance in the peripheral arterioles (1). Aware that stimulation of the sympathetic nervous system and the adrenal medulla can cause vasoconstriction, investigators have suggested a causal relationship between these activities and hypertension (2). There is little doubt that stress aggravates the hypertensive condition in the majority of patients, independently of etiologic factors. Many studies have shown that psycho-emotive disturbances have a significant effect by causing variations in cardiac output and peripheral vasoconstriction (3).Sodium chloride metabolism also has important influence on hypertension. Excessive sodium can greatly intensify the degree of blood pressure elevation. Conversely, dietetic restriction of sodium often reduces blood pressure in chronic hypertension (4). To a limited degree, hypertension can be controlled by reducing sodium concentration, whether by dietary restriction or by saluretic drugs.Many of the present antihypertensive drugs interfere with sympathetic innervation; that is, they act as ganglion-blocking agents (5). The use of these drugs, however, has greatly diminished because of the attendant side eff ects-dry mouth, visual aberrations, constipation and intestinal hypomotility (6). A new drug, mebutamate' (2-methyl-2-sec-butyl-l , 3-propanediol dicarbamate) possesses few, if any, toxic properties and lowers blood pressure by producing vasodilatation (7). Its action is mediated through the vasomotor center within the hypothalamus and medulla and not by direct action upon the peripheral vessels or ganglia (8). Mebutamate also offers the advantage of not altering cardiac output. To enhance therapeutic effects, it has been prepared in a combination form (Caplaril) with hydrochlorothiazide, a well recognized, clinically proven diuretic (9).The purpose of this study was to determine the effect of mebutamate used concomitantly with hydrochlorothiazide in hypertensive patients. MATERIAL AND METHODSThirty-six hypertensive subjects (18 men and 18 women) were studied. Their ages ranged from 33 to 72 years, with an average of 57.6 years. Ten patients had essential hypertension, * The mebutamate-hydrochlorothiazide combination used in this study was supplied in the form of Caplaril through the courtesy