INDAPAMIDE IMPROVES FLOW-INDUCED DILATION IN HYPERTENSIVE RATS WITH AHIGH-SALT INTAKE

Objective Spontaneously hypertensive rats (SHR) are sensitive to a hig h salt intake and we investigated the question of whether flow-induced dilation is affected by this type of diet, as flow responses are espe cially sensitive to small changes in extracellular sodium concentratio ns. Methods We evaluated the effects of a diuretic (indapamide, 1.5 mg /kg per day, 8 weeks) on four groups of SHR (n = 42). One group was fe d with a normal-salt diet (0.4%, control group, n=10), the second with a high-sodium diet (8%, n = 12), the third with a high-sodium diet an d indapamide (1.5 mg/kg per day, 8% salt, n = 10) and the fourth group was fed with indapamide alone (1.5 mg/kg per day, n = 10), The respon se to flow was studied in mesenteric resistance arteries (146 +/- 6.1 mu m internal diameter, pressure 100 mmHg) cannulated in vitro in an a rteriograph, Results The increase in mean arterial pressure (from 186 +/- 4 to 218 +/- 6 mmHg; P < 0.01) and heart weight:body weight ratio (3.48 +/- 0.09 versus 4.34 +/- 0.1 mg/g; P < 0.01) caused by the high salt intake was prevented by indapamide. A high salt intake significan tly decreased flow-induced dilation (6 +/- 0.8 versus 10.7 +/- 1.2 mu m dilation with a flow of 160 mu l/min; P < 0.05), while indapamide si gnificantly prevented the decrease in flow-induced dilation in high-sa lt SHR, Indapamide had no significant effect on flow-induced dilation in mesenteric resistance arteries from SHR with a normal-salt diet. Co nclusions Indapamide prevented the decrease in flow-induced dilation c aused by a high-salt diet, Therefore, indapamide might counteract the disturbance in sodium-sensitive flow sensor(s), through a diuretic eff ect. (C) 1998 Lippincott Williams & Wilkins.