Protein kinase C-epsilon primes the cardiac sarcolemmal adenosine triphosphate-sensitive potassium channel to modulation by isoflurane.
BACKGROUND
Cardioprotection by volatile anesthetic-induced preconditioning is known to involve intracellular signaling pathways. Recent studies have shown that protein kinase C (PKC) plays an important role in anesthetic-induced preconditioning. In this study, the effects of the activation of specific isozymes of PKC, specifically PKC-epsilon and -delta, on the modulation of the sarcolemmal adenosine triphosphate-sensitive potassium (sarcKATP) channel by isoflurane were investigated.


METHODS
The sarcKATP current was measured in ventricular myocytes isolated from guinea pig hearts using the whole cell configuration of the patch clamp technique. Peptides that induced the translocation of specific PKC isozymes were used to activate PKC-epsilon and PKC-delta.


RESULTS
Under whole cell conditions, isoflurane alone was unable to elicit the opening of the sarcKATP channel. Pretreatment with the specific PKC-epsilon activator, PP106, primed the sarcKATP channel to open in the presence of isoflurane. The resulting sarcKATP current densities in the presence of 0.88 mm isoflurane were 6.5 +/- 6.0 pA/pF (n = 7) and 40.4 +/- 18.2 pA/pF (n = 7) after pretreatment with 100 and 200 nm PP106, respectively. The PKC-epsilon antagonist PP93 abolished this effect. A scrambled peptide of the PKC-epsilon activator PP105 did not prime the sarcKATP channel. The PKC-delta activator PP114 was significantly less effective in priming the sarcKATP channel. 5-Hydroxydecanoate significantly attenuated the effect of the PKC-epdsilon activator on the sarcKATP channel. In addition, immunohistochemical analysis showed that the PKC-epsilon isoform translocated to both the mitochondria and sarcolemma after anesthetic-induced preconditioning, whereas the PKC-delta isoform translocated to the mitochondria.


CONCLUSIONS
The PKC-epsilon isozyme primed the sarcKATP channel to open in the presence of isoflurane. The PKC-delta isozyme was significantly less effective in modulating the isoflurane effect on this channel.
Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
Kei
K
Aizawa
Lawrence A
LA
Turner
Dorothee
D
Weihrauch
Zeljko J
ZJ
Bosnjak
Wai-Meng
WM
Kwok
D018528:ATP-Binding Cassette Transporters; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D002469:Cell Separation; D003652:Decanoic Acids / Q000494:pharmacology; D004594:Electrophysiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005455:Fluorescent Antibody Technique; D006168:Guinea Pigs; D006321:Heart / Q000502:physiology*; D006880:Hydroxy Acids / Q000494:pharmacology; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007530:Isoflurane / Q000494:pharmacology*; D054086:KATP Channels; D008297:Male; D009206:Myocardium / Q000166:cytology / Q000201:enzymology*; D018408:Patch-Clamp Techniques; D010703:Phorbol Esters / Q000494:pharmacology; D015221:Potassium Channels / Q000502:physiology*; D024661:Potassium Channels, Inwardly Rectifying; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D051745:Protein Kinase C-delta; D051744:Protein Kinase C-epsilon; D021381:Protein Transport / Q000502:physiology; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*
D018528:ATP-Binding Cassette Transporters; D018685:Anesthetics, Inhalation; D003652:Decanoic Acids; D004791:Enzyme Inhibitors; D006880:Hydroxy Acids; D054086:KATP Channels; D010703:Phorbol Esters; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; C092520:uK-ATP-1 potassium channel; C052853:5-hydroxydecanoic acid; D007530:Isoflurane; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D051744:Protein Kinase C-epsilon