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Hypoxic preconditioning upregulates KATP channels through activation of protein kinase C in rat ventricular myocytes
J G Zhuang1, Y Zhang, Z N Zhou
1Shanghai Institute of Physiology, Chinese Academy of Sciences, Shanghai 200031, China.
Aim:
To test: 1) if hypoxic preconditioning upregulates the activity of KATP channels in isolated adult rat cardiac myocytes; 2) if the upregulation involves protein kinase C (PKC).
Methods:
By the whole-cell patch-clamp recording technique, KATP channel currents (IKATP) were measured in the cardiomyocytes with no pretreatment (CON), hypoxic exposure preceding reoxygenation (HPC), phorbol 12-myristate 13-acetate (PMA), and chelerythrine addition with HPC (CH + HPC), respectively.
Results:
At 0 mV and 5 min after 2, 4-dinitrophenol (DNP) perfusion, the membrane currents for the CON, HPC, PMA, and CH + HPC were (3.5 +/- 1.9), (7.7 +/- 1.5), (7.5 +/- 3.3), (4.6 +/- 2.4) nA, respectively. Compared with the CON, the IKATP in the HPC and PMA were significantly augmented (P < 0.01) while the IKATP in the CH + HPC remained similar to the CON (P > 0.05).
Conclusion:
1) hypoxic preconditioning stimulated the activity of PKC and markedly enhanced the activity of KATP channels in the isolated rat cardiac myocytes; 2) PKC activation was involved in the upregulation of KATP channels.
