Antidiuretic and antinatriuretic response to high salt load in normotensive Wistar-Kyoto rats: Role of alpha-1A-adrenoreceptors

Summary Altered renal adrenergic responses have been recognized as pathophysiological responses to high salt intake. This study aims to investigate the influence of 6 weeks of high salt diet on α1A-adrenoceptor regulation of renal tubular antinatriuretic and antidiuretic response in normal Wistar Kyoto rats. To achieve the above objective, antinatriuretic and antidiuretic response to phenylephrine was measured in the absence and presence of 5-methylurapidil (5-MeU) using the inulin clearance method. Systemic mean arterial blood pressure and renal haemodynamics were also measured simultaneously. Six weeks of high salt intake in Wistar-Kyoto (WKY) rats did not bring any significant increase in mean arterial blood pressure. WKY rat on high salt diet (WKYHNa) showed an exaggerated increase in absolute and fractional sodium excretion. There was a significant involvement of α1A-adrenoceptor in carrying out renal tubular antinatriuretic and antidiuretic response in Wistar Kyoto rats on normal sodium diet (WKYNNa). However, α1A-adrenoceptor played a minimal role in handling the tubular reabsorptive response in WKY rats on high salt diet.