Adrenergic receptors on cultured rat epididymal cells: regulation of Cl- conductances.
Adrenergic regulation of epididymal Cl- currents was studied by the whole-cell patch-clamp technique using various alpha- and beta-receptor agonists and antagonists in primary cultured rat cauda epididymal cells. Cl- currents could be activated with varying frequency by noradrenaline (primarily alpha- and beta 1-adrenoceptor-selective agonist, 1-5 microM), isoprenaline (nonselective beta-adrenoceptor agonist, 5 microM), salbutamol (beta 2-adrenoceptor-selective agonist, 2 microM), and phenylephrine (alpha 1-adrenoceptor-selective agonist, 1-2 microM). Noradrenaline alone elicited Cl- current activation in 85% of the cells examined. In the presence of phentolamine (nonselective alpha-adrenoceptor antagonist, 15 microM), noradrenaline elicited Cl- current activation in 63% of the cells examined, whereas noradrenaline-induced activation was observed in 33% of the cells examined in the presence of both atenolol and butoxamine (beta 1- and beta 2-adrenoceptor antagonists, respectively, 10 microM). In 27% of single cells examined, a second current activation in response to salbutamol was observed after the first response to phenylephrine. When the order of stimuli was reversed, dual activation was also observed in 22% of the single cells examined, indicating the presence of both alpha- and beta-adrenoceptors in single epididymal cells. Profiles of time- and voltage-dependent Cl- current upon activation by different adrenoceptor agonists exhibited characteristics similar to those previously reported for Ca2+ and cAMP-activated Cl- currents, suggesting that regulation of epididymal Cl- conductances could be mediated by different adrenoceptor subtypes involving Ca2+ and cAMP as intracellular second messengers.
Chan
H C
HC
Department of Physiology, Faculty of Medicine, Chinese University of Hong Kong, Shatin, N.T.
Fu
W O
WO
Chung
Y W
YW
Zhou
T S
TS
Wong
P Y
PY
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000420:Albuterol / Q000494:pharmacology; D000818:Animals; D002078:Butoxamine / Q000494:pharmacology; D002478:Cells, Cultured; D018118:Chloride Channels / Q000032:analysis / Q000187:drug effects / Q000502:physiology*; D004822:Epididymis / Q000737:chemistry* / Q000166:cytology / Q000502:physiology; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011942:Receptors, Adrenergic, alpha / Q000032:analysis / Q000502:physiology*; D011943:Receptors, Adrenergic, beta / Q000032:analysis / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
D000316:Adrenergic alpha-Agonists; D018118:Chloride Channels; D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D002078:Butoxamine; D010656:Phenylephrine; D007545:Isoproterenol; D000420:Albuterol; D009638:Norepinephrine