Hypoxic preconditioning upregulates KATP channels through activation of protein kinase C in rat ventricular myocytes.
OBJECTIVE
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).


CONCLUSIONS
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.
Zhuang
J G
JG
Shanghai Institute of Physiology, Chinese Academy of Sciences, Shanghai 200031, China.
Zhang
Y
Y
Zhou
Z N
ZN
D000470:Alkaloids; D000818:Animals; D053119:Benzophenanthridines; D004789:Enzyme Activation; D006352:Heart Ventricles; D019157:Ischemic Preconditioning, Myocardial; D008297:Male; D009206:Myocardium / Q000166:cytology*; D018408:Patch-Clamp Techniques; D010617:Phenanthridines / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects*; D011493:Protein Kinase C / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000470:Alkaloids; D053119:Benzophenanthridines; D010617:Phenanthridines; D015221:Potassium Channels; C016299:chelerythrine; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate