TY - JOUR
T1 - Clonidine inhibits fluid absorption in the rabbit proximal convoluted renal tubule
AU - Rouse, Diane
AU - Williams, Shirley
AU - Suki, Wadi N.
N1 - Funding Information:
The results of this study were presented in part at the 17th annual meeting of the American Society of Nephrology in Washington, D.C., 1984, and appear in abstract form in Kidney International 27:333, 1985. The study was supported by grants from the National Institute of Health (AM21394 and DK 37543) and United States Public Health Service (RR-05425).
PY - 1990/7
Y1 - 1990/7
N2 - Previous studies have shown that norepinephrine (NE) and the beta-adrenoceptor agonist, isoproterenol (I), enhance fluid absorption (Jv) in isolated, perfused proximal convoluted tubule segments (PCT). Pretreatment of PCT with the beta-adrenoceptor antagonist, propranolol, inhibited the action of NE and produced a significant decline in Jv, suggesting modulation of Jv by both alpha- and beta-adrenoceptors. The present studies further characterize the alpha-adrenoceptor control of Jv in isolated perfused PCT using specific agonists and antagonists. Basal Jv declined significantly with the addition of the alpha2-adrenoceptor agonist, clonidine (10-4 M), to the bath; however, it was unchanged with the addition of the alpha1-adrenoceptor agonist, methoxamine (10-6 or 10-4 M). With the addition of 10-6 M isoproterenol Jv increased significantly, and returned to control values with the subsequent addition of clonidine (10-6 or 10-4 M). Pretreatment of PCT with the alpha2-adrenoceptor antagonist, yohimbine (10-5 M), or with pertussis toxin (100 ng/ml) did not interfere with the stimulation of Jv by isoproterenol, but abolished the inhibition of isoproterenol-stimulated Jv by clonidine. Thus, clonidine inhibits Jv in PCT via an alpha2-adrenoceptor. This effect is mediated by a pertussis toxin inhibitable GTP-binding protein, but not one that is coupled to adenylyl cyclase.
AB - Previous studies have shown that norepinephrine (NE) and the beta-adrenoceptor agonist, isoproterenol (I), enhance fluid absorption (Jv) in isolated, perfused proximal convoluted tubule segments (PCT). Pretreatment of PCT with the beta-adrenoceptor antagonist, propranolol, inhibited the action of NE and produced a significant decline in Jv, suggesting modulation of Jv by both alpha- and beta-adrenoceptors. The present studies further characterize the alpha-adrenoceptor control of Jv in isolated perfused PCT using specific agonists and antagonists. Basal Jv declined significantly with the addition of the alpha2-adrenoceptor agonist, clonidine (10-4 M), to the bath; however, it was unchanged with the addition of the alpha1-adrenoceptor agonist, methoxamine (10-6 or 10-4 M). With the addition of 10-6 M isoproterenol Jv increased significantly, and returned to control values with the subsequent addition of clonidine (10-6 or 10-4 M). Pretreatment of PCT with the alpha2-adrenoceptor antagonist, yohimbine (10-5 M), or with pertussis toxin (100 ng/ml) did not interfere with the stimulation of Jv by isoproterenol, but abolished the inhibition of isoproterenol-stimulated Jv by clonidine. Thus, clonidine inhibits Jv in PCT via an alpha2-adrenoceptor. This effect is mediated by a pertussis toxin inhibitable GTP-binding protein, but not one that is coupled to adenylyl cyclase.
UR - https://www.scopus.com/pages/publications/0025283887
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U2 - 10.1038/ki.1990.170
DO - 10.1038/ki.1990.170
M3 - Article
C2 - 1974662
AN - SCOPUS:0025283887
SN - 0085-2538
VL - 38
SP - 80
EP - 85
JO - Kidney international
JF - Kidney international
IS - 1
ER -