Interleukin-2 altered the frequency -dependent relationship of intracellular calcium in rat ventricular myocytes
- VernacularTitle:白细胞介素-2改变心肌细胞钙瞬态的频率依赖性
- Author:
Chunmei CAO
;
Qiang XIA
;
Yueliang SHEN
;
Zhiguo YE
;
Yuan LU
;
Junzhu CHEN
- Publication Type:Journal Article
- Keywords:
Interleukin-2;
Intracellular Ca 2+;
Myocardium;
R ats
- From:
Chinese Journal of Pathophysiology
2000;0(10):-
- CountryChina
- Language:Chinese
-
Abstract:
AIM: We examined the effect of interleukin- 2 (IL-2) on calcium handlin g of rat cardiomyocytes. METHODS: The effects of steady state an d transient chan ges in stimulus frequency on the intracellular calcium transient were investigat ed in the isolated ventricular myocytes with spectrofluorometry technique. RESULTS: Under the steady state (0.2 Hz), IL-2 at 2?10 5 U/L decr eased the peak [Ca 2+ ] i and amplitude of the [Ca 2+ ] i transient, increas ed the diastolic calcium level, and prolonged the decay of the calcium transient . At 1.25 mmol/L of extracellular [Ca 2+ ], when increasing the stimulus frequency from 0.2 to 1.0 Hz, diastolic calcium level and peak [Ca 2+ ] i as well as the amplitude of the transient were inc reased. The positive frequency relationship was blunted in the IL-2-treated myoc ytes and this was not normalized by increasing extracellular [Ca 2+ ] t o 2.5 mmol/L . The caffeine induced Ca 2+ release was increased with increase in stimu lus freq uency. IL-2 inhibited the frequency relationship of caffeine induced Ca 2+ releas e. The restitution was not different between control and IL-2 groups at the 1.25 mmol/L of extracellular [Ca 2+ ], which was slowed in IL-2-treated myo cytes when t he extracellular [Ca 2+ ] was increased to 2.5 mmol/L. CONCLUSIO NS: It is concluded that the blunted frequency response of IL-2-treated myocytes was resulted from the decrease in SR Ca 2+ release, which was related to depression of SR funct ion. Despite the evidence of depressed SR Ca 2+ uptake, the restitution o f ca lcium transient at 1.25 mmol/L of extracellular [Ca 2+ ] remains uncha nged, which maybe due to the increase in the Na +/Ca 2+ exchanger activi ty.
