Selective potentiation of angiotensin-induced constriction of skeletal muscle resistance arteries by chronic elevations in dietary salt intake

Sprague-Dawley rats were fed either a high-salt (HS, 4.0% NaCl) or a low-sa lt (LS, 0.4% NaCl) diet for 3 days (short-term) or 4-8 weeks (chronic). Vas oconstrictor responses to angiotensin II and norepinephrine were determined in isolated skeletal muscle resistance arteries and in distal arterioles o f the in situ cremaster muscle. Myogenic responses to increases in transmur al pressure were also assessed in skeletal muscle resistance arteries of an imals on high- or low-salt diets. Chronic (but not short-term) HS diet sele ctively potentiated angiotensin II-induced constriction of skeletal muscle resistance arteries relative to vessels from LS controls. Myogenic response s and norepinephrine-induced constriction of resistance arteries were unaff ected by either chronic or short-term HS diet. Constriction of cremasteric arterioles in response to angiotensin II and norepinephrine was unaffected by chronic or short-term elevations in dietary salt intake. These data sugg est that chronic elevations in dietary salt intake lead to a selective incr ease in the constriction of skeletal muscle resistance arteries to angioten sin II that may allow these vessels to continue to regulate their tone in r esponse to this peptide, despite the suppression of angiotensin II that occ urs with high-salt diet. (C) 1999 Academic Press.