EFFECTS OF MAXEPA ON SALT-INDUCED HYPERTENSION - RELATIONSHIP TO [H-3] NITROBENZYLTHIOINOSINE BINDING-SITES

We investigated the effects of dietary MaxEPA (a major source of eicos apentaenoic acid in fish oil) supplementation on blood pressure (BP) r esponses and heart rate (HII) of Dahl. salt-sensitive (SS) rats fed lo w (0.4% NaCl) and high (8.0% NaCl) sodium diets. During a four week tr eatment period, BP remained normotensive in rats on low salt diet but was significantly elevated in those on high salt diet, causing 50% mor tality. MaxEPA diminished the BP elevation and prevented the high salt -induced mortality. HR was not affected by either salt diet alone but was reduced in the presence of MaxEPA. At the end of the treatment per iod, the distribution of [H-3]nitrobenzylthioinosine ([H-3]NBMPR) bind ing, a putative marker of adenosine transport and metabolism, was esti mated in selected rat tissues in order to evaluate the role of the pur inergic system in the BP lowering effect of MaxEPA. Maximal [H-3]NBMPR binding capacity (Bmax) in the kidney and platelets were 39% and 82% lower, respectively, in rats on high salt diet than in those on low sa lt diet. MaxEPA significantly blunted the decrease in Bmax in the kidn ey but not in platelets and increased Bmax in heart (48%) of low salt group. There were no changes in dissociation constants (Kd). The resul ts suggest that MaxEPA can attenuate salt-induced hypertension, reduce salt-induced mortality and protect the integrity of kidney NBMPR bind ing sites in salt-induced hypertension.