Short- and long-term effects of reserpine on rat cardiac beta-adrenoceptors.
1. In order to explore the mechanism of reserpine-induced supersensitivity, we examined the effects of various doses of reserpine (R) on rat cardiac beta-adrenoceptors (beta AR). 2. 24 hr after a single administration of R (1 mg/kg, i.p.) beta AR were up-regulated, while with higher doses (2.5-5 mg/kg) beta AR density was not changed but beta AR coupling, evaluated by the proportion of high-affinity agonist binding states, was impaired. 3. Long-term effects of R (2.5 mg/kg/day, 2 days) included beta AR down-regulation and uncoupling 24 hr treatment (day 1), followed by up-regulation at day 7, while all parameters were similar to controls at day 14. 4. It appears that R induces either an increase or a decrease of cardiac beta AR density and coupling, dependent on the dose and the time at which beta AR are measured after treatment.
Cros
G H
GH
Laboratoire de Pharmacodynamie, Faculté de Pharmacie, Montpellier, France.
Chanez
P O
PO
McNeill
J H
JH
Serrano
J J
JJ
D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D006321:Heart / Q000187:drug effects*; D020120:Iodocyanopindolol; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008566:Membranes / Q000187:drug effects; D010869:Pindolol / Q000031:analogs & derivatives; D051381:Rats; D011919:Rats, Inbred Strains; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*; D012110:Reserpine / Q000494:pharmacology*
D011943:Receptors, Adrenergic, beta; D020120:Iodocyanopindolol; D012110:Reserpine; D010869:Pindolol; D007545:Isoproterenol