Effects of long-term application of dopamine HCl on dopamine agonist-induced cAMP production in rat renal cortex.
OBJECTIVE
To study the effects of long-term application of dopamine HCl (DA) on the functional changes of dopamine receptor subtypes coupled to adenyl cyclase in rat renal cortex.


METHODS
cAMP levels were measured by radioimmunoassay as an index of dopamine receptor function.


RESULTS
Injection of DA (30 mg.kg-1.d-1, i.p. 30 d) reduced the fenoldopam (Fen) (100 mumol.L-1)-induced increments of cAMP production from the control group of +1.26 +/- 0.04 to the DA-treated group of +0.63 +/- 0.22 nmol.min-1/g tissue and the propyl-butyl-dopamine (PBDA) (100 mumol.L-1)-induced decrements of cAMP production in the presence of Sch-23390 (Sch) from the control group of -0.38 +/- 0.18 to the DA-treated group of -0.11 +/- 0.08 nmol.min-1/g tissue with, however, comparable percentile changes for the 2 groups. Sch blocked both Fen- and PBDA-induced increase in cAMP production, while domperidone (Dom) blocked the decreasing effects of PBDA on cAMP accumulation in the presence of Sch.


CONCLUSIONS
Long-term application of DA produced a marked "down regulation" of both DA1 and DA2 receptors in rat renal cortex with, however, the responsiveness of the remaining receptors unchanged.
Zhao
R R
RR
Department of Physiology, Shanxi Medical University, Taiyuan, China.
Jin
X H
XH
Zhu
L
L
Wang
W Z
WZ
D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D000242:Cyclic AMP / Q000096:biosynthesis*; D004294:Domperidone / Q000494:pharmacology; D004298:Dopamine / Q000031:analogs & derivatives / Q000494:pharmacology*; D018491:Dopamine Agonists / Q000494:pharmacology*; D018492:Dopamine Antagonists / Q000494:pharmacology; D018818:Fenoldopam / Q000037:antagonists & inhibitors; D007672:Kidney Cortex / Q000378:metabolism*; D008297:Male; D051381:Rats; D017208:Rats, Wistar
D001552:Benzazepines; D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D004294:Domperidone; C016080:N-n-propyl-N-n-butyl-beta-dopamine; D000242:Cyclic AMP; D018818:Fenoldopam; D004298:Dopamine