Stimulating effects of dopamine on chloride transport across the rat caudal epididymal epithelium in culture.
The present study investigated the effects of dopamine on chloride transport across cultured rat caudal epididymal epithelium. The results showed that dopamine induced a biphasic short-circuit current (Isc) in a concentration-dependent manner. The dopamine-induced response consisted of an initial rapid spike followed by a sustained phase. The alpha and beta adrenoreceptor inhibitors, phentolamine and propranolol, inhibited the initial spike and the sustained phase, respectively, suggesting a contribution of adrenergic receptors. The response was almost abolished by removing the extracellular Cl-, suggesting that the dopamine-induced short-circuit current is primarily a Cl- current. The response was inhibited by the apical Cl- channel blocker, diphenylamine-dicarboxylic acid, and the Ca2+-activated Cl- channel blocker, disulfonic acid stilbene, indicating that Cl- may pass through two types of Cl- channels on the apical side. Preloading monolayers with the intracellular Ca2+ chelator BAPTA/AM abolished the initial spike and greatly reduced the second phase in the Isc response to dopamine. Pretreating the monolayers with an adenylate cyclase inhibitor, MDL12330A, inhibited all of the second Isc response and part of the initial spike. Also, characteristics of the Cl- currents induced by dopamine were observed in whole-cell patch-clamp recording. The increases of intracellular cAMP and Ca2+ induced by dopamine were also measured. The results suggest that extracellular dopamine activates Ca2+-dependent and cAMP-dependent regulatory pathways, leading to activation of both Ca2+-dependent and cAMP-dependent Cl- conductances in epididymal epithelial cells.
Du
Jian-Yang
JY
School of Life Science, Sun Yat-sen University, Guangzhou 510275, China.
Zuo
Wu-Lin
WL
Ruan
Ye-Chun
YC
Yang
Zi-Huan
ZH
Chen
Min-Hui
MH
Chen
Si-Liang
SL
Li
Sheng
S
Wu
Zhong-Luan
ZL
Xiang
Hui
H
Zhou
Wen-Liang
WL
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D018674:Adrenergic Antagonists / Q000494:pharmacology; D000818:Animals; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism; D004298:Dopamine / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004822:Epididymis / Q000187:drug effects* / Q000378:metabolism; D007097:Imines / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D018408:Patch-Clamp Techniques; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D062367:ortho-Aminobenzoates / Q000494:pharmacology
D018674:Adrenergic Antagonists; D018118:Chloride Channels; D002712:Chlorides; D004791:Enzyme Inhibitors; D007097:Imines; D062367:ortho-Aminobenzoates; C014925:RMI 12330A; C001209:fenamic acid; D011433:Propranolol; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D004298:Dopamine; D010646:Phentolamine