Theophylline-induced stimulation of sodium transport in frog skin by a mechanism different from the antidiuretic hormone activated pathway.
Theophylline (theo) induced a marked increase in the short circuit current (SCC) after maximal stimulation by the antidiuretic hormone, arginine vasotocin (AVT). The stimulation amounted to 20-70% of the AVT-stimulation. Practically no effect was seen on osmotic water flow after maximal AVT-stimulation. A concentration dependence of the SCC stimulation was found from 0.04 to 4 mM theo, 16 mM inhibited the SCC. The response to theo was independent of the time of preincubation with AVT. The theo induced increase of SCC was accounted for by active sodium transport. Theo did induce an increase in the cyclic AMP level after stimulation with a maximal concentration of AVT, but so did a supramaximal dose of AVT. This indicates that the mechanism, by which theo stimulated the SCC additional to maximal AVT stimulation, is different from that by which AVT works. This effect of theo may be unrelated to cAMP or it may be explained by differences in cellular specificity of theo and AVT.
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D000242:Cyclic AMP / Q000378:metabolism; D011893:Rana esculenta; D011896:Rana temporaria; D012867:Skin / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D013806:Theophylline / Q000494:pharmacology*; D014667:Vasopressins / Q000494:pharmacology*; D014668:Vasotocin / Q000494:pharmacology
D014667:Vasopressins; D012964:Sodium; D013806:Theophylline; D000242:Cyclic AMP; D014668:Vasotocin