Hypoxia facilitates rapid pacing-induced calcium transient alternations in ventricular myocytes |
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Authors: | ZHAO Bin WANG Li-chun ZHUANG Xiao-dong DONG Xiao-bian HUANG Ze-na KUANG Su-juan LIU Xiao-ying LIAO Xin-xue |
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Institution: | 1. Department of Cardiovasology, Department of Hypertension and Vascular Disease, the First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510080, China;2. Medical Research Center of Guangdong General Hospital, Guangzhou 510080, China |
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Abstract: | AIM:To explore the effect of hypoxia on rapid pacing-induced calcium transient alternations in ventricular myocytes.METHODS:Ventricular myocytes were isolated from the heart of adult SD rats and cultured in serum-free hypoxic fluid to set up an in vitro model of hypoxia-induced cardiac injury. The calcium transient and its alternations were investigated under confocal laser scanning microscope. The mitochondrial function was also examined by WST-8 kit. RESULTS:Under normoxic condition, the ventricular myocytes were claviform. Low frequency of pacing, ranging from 60 to 240 min-1, induced calcium transient, but not calcium transient alternations, which was elicited by the pacing over a threshold frequency of(288 ±27)min-1. Exposure of the ventricular myocytes to hypoxia did not obviously affect the morphology of the cells, but reduced the threshold frequency of pacing to(227±26) min-1(P<0.05). Additionally, exposure of the cells to hypoxia repressed the activity of mitochondrial dehydrogenase from(100.2±8.7)%(control group) to(57.6±7.5)%, which was partially blocked by L-type Ca2+ channel inhibitor. CONCLUSION:Hypoxia facilitates calcium transient alternations induced by rapid pacing, and the calcium transient alternations are involved in the hypoxia-injured mitochondria function. |
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Keywords: | Hypoxia Rapid pacing Calcium transient alternations Mitochondria Ventricular myocytes |
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