Influence of chronic treatment of rats with isoprenaline and calcium channel blockers on response of isolated right ventricle to noradrenaline.
Indian J Exp Biol
;
2001 Mar; 39(3): 272-5
Article
in English
| IMSEAR
| ID: sea-57867
ABSTRACT
Influence of chronic treatment of rats with and calcium channel blockers (CCBs) and isoprenaline (ISP) on responses to noradrenaline (NA) was investigated on electrically--driven isolated right ventricle preparations. The ventricles were obtained from animals treated with chronic ISP or CCBs alone and chronic nifedipine, verapamil, diltiazem or nimodipine plus chronic ISP. A decreased response to NA as evidenced by an increase in EC50 for contraction which was observed in chronic ISP- treated preparations may be due to development of desensitisation (down-regulation) of beta-adrenoceptors. In chronic CCB-treated preparations there was a significant decrease in the EC50 of NA and decreased contractile response suggesting an increase in the beta-adrenoceptors and decreased availability of calcium, respectively. In chronic CCBs + ISP treated preparations further decreases in the EC50 values were observed suggesting that the voltage gated L-type Ca2+ channels may be affected directly or indirectly by change in beta-adrenoceptor activity. By the above results a proposed mechanism of interrelationship of beta-adrenoceptors with voltage gated L-type calcium channels in cardiac muscle is supported.
Full text:
Available
Index:
IMSEAR (South-East Asia)
Main subject:
Rats
/
Male
/
Calcium Channel Blockers
/
Norepinephrine
/
Rats, Wistar
/
Calcium Channels, L-Type
/
Heart
/
Isoproterenol
/
Animals
/
Myocardial Contraction
Language:
English
Journal:
Indian J Exp Biol
Year:
2001
Type:
Article
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