Effects of verapamil on down-regulation of norepinephrine-induced beta adrenoceptors in cultured rat cardiomyocytes.
OBJECTIVE
To determine whether verapamil (Ver) inhibits norepinephrine (NE)-induced beta adrenoceptors down-regulation in cultured rat cardiomyocytes.


METHODS
[3H]-Dihydroalprenolol (DHA) radiobinding assay was used to measure beta adrenoceptor density, fluorescent indicator Fura 2-AM was used to estimate levels of free cytosolic calcium ([Ca2+]i).


RESULTS
Ver reduced [Ca2+]i and increased beta adrenoceptor density, NE increased [Ca2+]i and reduced beta adrenoceptor density of cultured cardiomyocytes, these effects were time and concentration dependent. Ver inhibited the above effects of NE.


CONCLUSIONS
Ver increased beta adrenoceptor density and inhibited NE-induced beta adrenoceptor down-regulation of cardiomyocytes.
Xu
B
B
Department of Cardiology, Affiliated Hospital of Nanjing Railway Medical College, China. b.xu@umds.ac.uk
Zhang
S L
SL
Chen
R X
RX
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002478:Cells, Cultured; D015536:Down-Regulation; D005260:Female; D008297:Male; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D009638:Norepinephrine / Q000037:antagonists & inhibitors; D051381:Rats; D017207:Rats, Sprague-Dawley; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D014700:Verapamil / Q000494:pharmacology*
D000316:Adrenergic alpha-Agonists; D002121:Calcium Channel Blockers; D011943:Receptors, Adrenergic, beta; D014700:Verapamil; D002118:Calcium; D009638:Norepinephrine