?-adrenoceptor desensitization and changes of calcium transient in rat ventricular myocytes following chronic hypoxia
- VernacularTitle:低氧后心肌钙瞬变变化与?-肾上腺素受体脱敏的关系
- Author:
Jianming PEI
;
Yuemin WANG
;
Heng MA
;
Hui BI
;
Miaozhang ZHU
- Publication Type:Journal Article
- Keywords:
Receptors, adrenergic, beta;
Desensitization;
Calcium;
Myocardium;
Anoxia
- From:
Chinese Journal of Pathophysiology
1986;0(04):-
- CountryChina
- Language:Chinese
-
Abstract:
AIM: The present study was to investigate the time course of ?-adrenoceptor desensitization and changes in the calcium transient in rat ventricular myocytes following chronic hypoxia. METHODS: With the spectrofluorometric method, the intracellular calcium( i) transient and its response to ?-adrenoceptor stimulation were determined in the single right ventricular myocytes, loaded with Fura-2.RESULTS: After 2-3 weeks of chronic hypoxia, the amplitudes of electrically induced i transient and caffeine-induced i transient started to decrease and the duration of i transient prolonged. The enhanced electrically induced i transient evoked by isoprotrenol was also decreased. After 3 or 4 weeks of chronic hypoxia, these changes aggravated gradually. After 8 weeks of chronic hypoxia, the changes of all these parameters were convalescent, meanwhile there was no significant difference compared with that of 4 weeks group. CONCLUSIONS: After 2-4 weeks of chronic hypoxia, the ?-adrenoceptor desensitization occurs, the underlying mechanism is related to the decreased function of L-type of calcium channel, ryanodine receptor-operated calcium channel and calcium ATPase, which is responsible for the decreased cardiac functionl. At 8 weeks of hypoxia, the heart is in adaptation and compensatory process.
