Extrarenal salt excretion in sea snakes (Laticauda)

Abstract

Extrarenal and renal routes of electrolyte excretion were compared in the sea snake Laticauda semifasciata before and after sodium chloride or sucrose loading. The snakes were shown to have a functional salt gland. The smallest NaCl load which elicited salt gland secretion was 5 mmoles/ 100 g body weight, injected subcutaneously. An osmotically equivalent sucrose load had the same stimulatory effect on the rate of salt gland secretion as did the NaCl load. This indicated that an osmoreceptor was involved with control of gland secretion. The maximum rate of extrarenal excretion of Na was 72 [mu]moles/100 g hr. Chloride was lost at the same rate. K was excreted at a much smaller rate, about 3 [mu]moles/100 g hr. Salt gland secretion was collected from the tip of the mouth between the rostral and mental scales whenever the tongue was extended. Morphological studies of Laticauda and Pelamis indicate that the salt gland is a previously undescribed gland lying in the midline, anterior to the interr nal choanae.