Dibutyryl Cyclic Adenosine Monophosphate Stimulates the Sodium Pump in Rabbit Renal Cortical Tubules

Abstract

The elevation in oxygen consumption (QO₂) observed following addition of the sodium ionophore nystatin in suspensions of rabbit renal proximal tubules was significantly increased by 1 mM dibutyryl cyclic adenosine monophosphate (db-cAMP). The QO₂ after subsequent addition of strophanthidin to block the sodium pump was unnaffected by db-cAMP. However, 10 µM forskolin in the presence of 100 µM IBMX had no significant effect on the QO₂ observed following addition of either nystatin or strophanthidin. Nevertheless, we can conclude that db-cAMP does stimulate the sodium pump activity independently of sodium transport mechanisms in the rabbit renal proximal tubule.

Stimulation of ouabain‐sensitive 86Rb+ uptake and Na+,K+‐ATPase α‐subunit phosphorylation by a cAMP‐dependent signalling pathway in intact cells from rat kidney cortex

“…These results indicated that PKA activation led to the stimulation of Na+,K+-ATPase in rat cortical renal cells. This finding is in agreement with recent studies showing a stimulatory effect of cAMP on proximal Na+,K+-ATPase activity estimated by oxygen consumption [12], basolateral membrane potential variation [3] or Na +,K +-ATPase [y-32p]ATP hydrolytic activity [13]. The increases in ion transport activity and in the degree of phosphorylation of the Na+,K+-ATPase suggest that cAMP modulates the enzyme activity by promoting the phosphorylation of its c~-subunit.…”

Protein kinase A induces recruitment of active Na+,K+‐ATPase units to the plasma membrane of rat proximal convoluted tubule cells

“…Our results are in agreement with studies demonstrating a stimulatory effect of cAMP on proximal tubule Na + ,K + ‐ATPase activity measured in intact cells by (a) ouabain‐sensitive oxygen consumption (Beck et al 1995), (b) Na + ,K + ‐ATPase‐dependent basolateral membrane potential variation (Breton et al 1994), (c) ouabain‐sensitive 8 6 Rb + uptake (Carranza et al 1996), or in permeabilized isolated PCTs (Bertorello & Aperia, 1988, 1989) and kidney cortex homogenate (Giesen et al 1984) by the hydrolytic activity of the enzyme. However, one study has reported inhibition of Na + ,K + ‐ATPase by db‐cAMP (Ribeiro & Mandel, 1992) while another one did not find any effect of either exogenous or endogenous cAMP on Na + ,K + ‐ATPase activity (Satoh et al 1993).…”

“…In PCT, short‐term stimulation of Na + ,K + ‐ATPase by conditions that activate PKA has been reported by several groups (Giesen et al 1984; Bertorello & Aperia, 1988; Breton et al 1994; Beck et al 1995; Carranza et al 1996) but the mechanisms have yet to be determined. Besides the possibility of an increase in Na + ,K + ‐ATPase activity due to the kinetic effect of a rise in intracellular Na + concentration (Skou, 1965), a change in the intrinsic properties of Na + ,K + ‐ATPase (Féraille et al 1995) or an increased number of active Na + ‐K + pump units expressed in plasma membranes (Hundal et al 1992) may explain the effect of PKA activation.…”

Renal Phosphodiesterase 4B Is Activated in the Dahl Salt-Sensitive Rat

“…Evidence suggests that ␤-adrenergic signaling promotes Na excretion by facilitating a blood-lumen flux of Na ϩ , 20 whereas other studies have indicated that ␤-adrenergic signaling inhibits Na ϩ uptake in tubules by stimulating basolateral Na/K ATPase. [22][23][24] Additional renal effects of rolipram that have been reported include regulation of the osmotic permeability response to antidiuretic hormone in neonatal tubules 25 and renin release from juxtaglomerular cells. 26 Both the Dahl SS rats and SHRs are generally considered to be models of renal hypertension.…”