Mode of action of parathyroid hormone and cyclic adenosine 3′,5′-monophosphate on renal tubular phosphate reabsorption in the dog

Abstract

ABSTRA CT To evaluate the effects of parathyroid hormone and cyclic adenosine monophosphate on proximal tubular sodium and phosphate reabsorption, micropuncture studies were performed on dogs that received a highly purified preparation of parathyroid hormone (PTH), dibutyryl cyclic 3',5'-adenosine monophosphate (cyclic AMP), 5'-AMP, and saline. PTH resulted in a 30-40% inhibition of sodium and phosphate reabsorption in the proximal tubule unassociated with a rise in either total kidney or single nephron glomerular filtration rate (GFR). The bulk of the phosphate rejected proximally was excreted in the final urine while sodium excretion rose minimally despite the marked proximal inhibition, consistent with the presence of reabsorptive sites in the distal nephron for sodium but not phosphate. The infusion of dibutyryl cyclic AMP either systemically or directly into the renal artery inhibited proximal sodium and phosphate reabsorption in the absence of changes in either total kidney or single nephron GFR, resembling the effects of PTH quantitatively and qualitatively. In contrast, another adenine nucleotide, 5'-AMP, did not inhibit the reabsorption of either sodium or phosphate. These observations support the thesis that renal effects of PTH are mediated via stimulation of renal cortical adenyl cyclase. The infusion of a moderate saline load, 25 ml/kg, also produced a similar inhibition of proximal tubular fractional sodium and phosphate reabsorption with a marked phosphaturia but only minimal natriuresis. Thus, changes in An abstract of this work was published previously (1970. J. Clin. Invest. 49: 77a.).

Renal adenylate cyclase and the interrelationship between parathyroid hormone and vitamin D in the regulation of urinary phosphate and adenosine cyclic 3',5'-monophosphate excretion.

“…Our experiments are at variance with those of Nagata and Rasmussen (9), who found that Fig. 4 Previous studies have shown that the phosphaturic action of PTH in TPTX rats can be produced through infusion of either dibutyryl cyclic AMP (2,(28)(29)(30) or theophylline (28). In addition, it has been reported that the phosphaturic response to both PTH and dibutyryl cyclic AMP is blunted in the D-deficient rat (2).…”

Physiological and molecular responses of the goldfish kidney (Carassius auratus) to metabolic acidosis, and potential mechanisms of renal ammonia transport

“…5C) rather than direct secretion of P i . In mammals (Strickler et al, 1964;Agus et al, 1971), changes in P i reabsorption similarly regulate the degree of urinary P i excretion. The decline of plasma Na + and Cl − in acid-exposed goldfish (Table 1) has been seen previously in other acid-exposed teleosts (McDonald et al, 1980;McDonald and Wood, 1981;Ultsch et al, 1981;Fugelli and Vislie, 1982;Wright et al, 2014).…”

Study of the Renal Tubular Interactions of Thyrocalcitonin, Cyclic Adenosine 3′, 5′ -Monophosphate, 25-Hydroxycholecalciferol, and Calcium Ion

“…It is now well established that two of the factors which are important in controlling phosphate, calcium, and sodium transport in the nephron are parathyroid hormone (PTH)' and the status of the extracellular fluid volume (1)(2)(3)(4)(5)(6)(7)(8)(9). The actions of PTH on renal transport can be largely, but not entirely reproduced by the administration of cyclic adenosine 3',5'monophosphate (cAMP) (10)(11)(12)(13)(14).…”