title: Aldosterone stimulates K secretion prior to onset of Na absorption in guinea pig distal colon.
abstract: Distal colon from guinea pig was stimulated in vitro by aldosterone in Ussing chambers that allowed measurement of short-circuit current (Isc) and tissue conductance (Gt). The response to aldosterone was delayed by approximately 20 min and resulted in a negative Isc, consistent with K secretion. Approximately 1 h later the Isc began to increase and eventually became positive, consistent with subsequent stimulation of Na absorption. The Na-absorptive response could be inhibited by mucosal amiloride without altering the rate of K secretion. Similarly, K secretion could be inhibited by serosal bumetanide without altering Na absorption. In the presence of spironolactone, actinomycin D, or cycloheximide, aldosterone failed to stimulate both K secretion and Na absorption. A dose response to aldosterone provided an apparent Kd of 2.6 +/- 0.5 nM, consistent with a high-affinity receptor coupled to this secretory response. Stimulation by the K secretagogue epinephrine did not produce an additive increase in K secretion, suggesting that the same cell type responds to both aldosterone and epinephrine and that the protein induced by aldosterone was not one of the membrane proteins responsible for K secretion.
authors.affiliation: Department of Physiology, Ohio State University, Columbus 43210.
authors.forename: D R
authors.initials: DR
authors.lastname: Halm
authors.forename: S T
authors.initials: ST
authors.lastname: Halm
mesh_terms: D000450:Aldosterone / Q000494:pharmacology*; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002034:Bumetanide / Q000494:pharmacology; D003106:Colon / Q000378:metabolism*; D006168:Guinea Pigs; D007408:Intestinal Absorption / Q000187:drug effects*; D008297:Male; D011188:Potassium / Q000378:metabolism*; D014176:Protein Biosynthesis; D018161:Receptors, Mineralocorticoid / Q000378:metabolism; D012964:Sodium / Q000493:pharmacokinetics*; D013997:Time Factors; D014158:Transcription, Genetic
chemical_list: D018161:Receptors, Mineralocorticoid; D002034:Bumetanide; D000450:Aldosterone; D000584:Amiloride; D012964:Sodium; D011188:Potassium