Vasopressin-related alterations of sodium reabsorption in the loop of Henle

The effect of vasopressin on phosphate transport in the proximal tubule of the dog.

“…The reasons for the variable blood pressure changes after vasopressin are unknown, but they may represent differences' in individual responsiveness to the given dose of vasopressin. An inhibitory effect of vasopressin on proximal tubule sodium reabsorption has not been demonstrated previously (4)(5)(6). The earlier micropuncture studies were carried out because there may be stimulation of sodium transport by vasopressin as suggested by toad bladder studies (14), but such a stimulatory effect could not be shown except in the isolated collecting tubules (15).…”

“…This strongly suggests that a distal effect of vasopressin on sodium transport was mainly responsible for the observed natriuresis. Indeed, such an inhibitory effect of vasopressin on distal nephron has been demonstrated by Antoniou, Burke, Robinson, and Clapp (6).…”

“…Because of the concomitant phosphaturia, they concluded that vasopressin exerts natriuresis by stimulating the production of cyclic AMP in the proximal tubule of the kidney, thereby reducing its sodium and phosphate reabsorption. On the other hand, the available micropuncture studies in the literature (4)(5)(6) failed to demonstrate any effect of vasopressin on proximal tubule sodium transport in the animals undergoing water diuresis. Our present micropuncture study was undertaken to reexamine whether proximal tubule transport of sodium and phosphate could be altered in thyroparathyroidectomized (TPTX) dogs by administration of vasopressin in the doses frequently employed in experimental conditions.…”

Effect of vasopressin on electrical potential difference and chloride transport in mouse medullary thick ascending limb of Henle's loop.

“…Although they concluded that this might reflect an AVPinduced inhibition of sodium transport, these authors also pointed out that the increased sodium delivery and concentration in the early distal tubule might reflect increased sodium entry into the loop of Henle during antidiuresis. Because the rate of solute delivery was unknown in the last study (40), the data obtained in the early distal tubule could not provide conclusive evidence for or against a change in active transport by the thick ascending limb. Furthermore, although there is no particular reason to doubt its presence, an AVPsensitive adenyl cyclase has not yet been demonstrated in the dog thick ascending limb.…”

“…The application of these data to the present question is complicated, however, by the reduced responsiveness to vasopressin recently observed in thick ascending limbs obtained from this strain of rat (39). Antoniou et al (40) found that both fractional delivery and concentration of sodium were increased in the early distal tubule after vasopressin administration to dogs. Although they concluded that this might reflect an AVPinduced inhibition of sodium transport, these authors also pointed out that the increased sodium delivery and concentration in the early distal tubule might reflect increased sodium entry into the loop of Henle during antidiuresis.…”