Up-regulation of Ca(2+) channels in vas deferens after chronic treatment of newborn rats with nifedipine.
Radioligand binding and contraction techniques were used to verify if L-type Ca(2+) channels are modified in rat vas deferens after treatment with the blocker nifedipine (15 microg), injected at 7, 14, 21 and 28 days after birth. Vas deferens tissue was used 10, 30 and 90 days after the last injection, to verify if modifications are persistent. Binding studies with cell membranes, using [(3)H]isradipine, showed an increase of the density (B(max)) of Ca(2+) channels by more than 60%, after 10 and 30 days, without changes of affinity (K(d)). Maximal contractions (E(max)) of KCl, were increased by 106% and 37%, respectively, after 10 and 30 days, without changes of apparent affinity (pD(2)). After 90 days, the values of B(max), K(d), E(max) and pD(2) were not different from the controls. Differences were also not found for rats injected when adult. It is concluded that treatment of newborn, but not of adult, rats with nifedipine produced a long-lasting, though reversible, up-regulation of L-type Ca(2+) channels.
Verde
Luciana Ferreira
LF
Department of Pharmacology, Federal University of São Paulo, São Paulo 04034-970, Brazil.
Lafayette
Simone S L
SS
Caricati-Neto
Afonso
A
Jurkiewicz
Neide H
NH
Jurkiewicz
Aron
A
D000818:Animals; D000831:Animals, Newborn; D002121:Calcium Channel Blockers / Q000008:administration & dosage / Q000494:pharmacology*; D020746:Calcium Channels, L-Type / Q000235:genetics / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D009543:Nifedipine / Q000008:administration & dosage / Q000494:pharmacology*; D011189:Potassium Chloride / Q000494:pharmacology; D011485:Protein Binding; D011869:Radioligand Assay; D051381:Rats; D017208:Rats, Wistar; D015854:Up-Regulation; D014649:Vas Deferens / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology
D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D011189:Potassium Chloride; D009543:Nifedipine