NACL APPETITE IN 2 STRAINS OF RAT REPORTED TO BE RESISTANT TO MINERALOCORTICOID-INDUCED HYPERTENSION

Both Long-Evans (LE) and Wistar-Furth (WF) strains of rat are known to be resistant 13 development of hypertension by mineralocorticoid (MC) treatment. MC-induced hypertension is, in pan, mediated by the brain. We have examined another aspect of central MC action, the induction o f NaCl appetite in these strains, by using the more common Sprague-Daw ley (SD) and Wistar (WS) strains for comparison. In the first experime nt, LE and SD rats were administered three treatments known to induce an appetite for NaCl solution in rats. Administration of deoxycorticos terone acetate (DOCA) increased the intake of 0.45 M NaCl in both stra ins, but the amounts consumed were about 2-fold greater in LE rats tha n in SD rats. Administration of captopril also increased NaCl intake, but there were no differences between LE and SD rats. NaCl depletion w ith furosemide induced NaCl appetite in both strains, but the amounts consumed were about 2-fold greater in LE rats than in SD rats. In the second experiment, adult male WF and WS rats were administered DOCA, e nalapril, or furosemide and NaCl appetite was determined. Both strains showed comparable NaCl appetite during each of these treatments. Howe ver, during a 5-week regimen of DOCA with only NaCl-KCl solution to dr ink, uninephrectomized WF rats consumed less than WS rats. Thus, despi te reported resistance to MC-induced hypertension, neither LE nor WF s trains of rats showed correspondingly marked deficits in induced NaCl appetite. (C) 1998 Elsevier Science Inc.