IMMUNOHISTOCHEMICAL CORRELATES OF PERIPHERAL GUSTATORY SENSITIVITY TOSODIUM AND AMILORIDE

In mammals, transduction of sodium stimuli occurs via amiloride-sensit ive sodium channels. In rat, gustatory physiological sensitivity to so dium stimuli develops gradually during the early postnatal period. In addition, if pregnant rats are subjected to dietary sodium restriction during gestation, their offspring fail to develop normal gustatory ph ysiological responses to sodium and sensitivity to amiloride. In the p resent study, we used polyclonal antibodies raised against amiloride-s ensitive sodium channels to ascertain whether gustatory function is co rrelated with the immunological presence of the transduction apparatus for sodium stimuli in the taste buds of neonatal rats and adult offsp ring of sodium-restricted dams. The results indicate that antiamilorid e-sensitive sodium channel antisera bind cells within taste buds of ne onatal and adult rats, regardless of maternal dietary condition. There fore, despite the functional absence of taste system amiloride-sensiti ve sodium channels, the antigenic determinants of these channels are e xpressed. These data suggest that the onset of normal gustatory sodium sensitivity in neonatal normal rats results from the progressive acti vation of existing, quiescent channels. Furthermore, they rule out the possibility that the failure to synthesize channel protein underlies the lack of gustatory sodium and amiloride sensitivity in the offsprin g of sodium-restricted rats.