Activation of the K+ channel BK(Ca) is involved in the relaxing effect of propofol on coronary arteries.
OBJECTIVE
Propofol may cause undesirable hypotension due to vasodilation. The underlying mechanisms are not completely understood. We investigated the mechanisms by which propofol relaxes vascular segments.


METHODS
We studied the effect of propofol on isolated porcine coronary artery rings precontracted with potassium chloride or prostaglandin F2alpha.


RESULTS
Propofol, in a concentration-dependent manner, relaxed all segments at concentrations of 5 microg mL(-1) and above. This relaxation was unaltered in the presence of N(omega)-nitro-L-arginine, indomethacin, diltiazem and glibenclamide. Tetraethylammonium chloride, an inhibitor of the BK(Ca) K+ channel (a high conductance Ca2+-sensitive K+ channel), dose-dependently attenuated the vasodilating effect of propofol (P < 0.001).


CONCLUSIONS
Our results suggests that the activation of the BK(Ca) channel may contribute to the vasodilating effect of propofol, hereby causing hyperpolarization of the smooth muscle membrane and reduction of smooth muscle tone.
Klockgether-Radke
A P
AP
Georg-August University of Göttingen, Centre of Anaesthesiology, Emergency and Intensive Care Medicine, Department of Anesthesiological Research, Göttingen, Germany. klockgether-radke@gmx.de
Schulze
H
H
Neumann
P
P
Hellige
G
G
D018686:Anesthetics, Intravenous / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D003331:Coronary Vessels / Q000187:drug effects*; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004110:Diltiazem / Q000494:pharmacology; D015237:Dinoprost / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005905:Glyburide / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D019335:Nitroarginine / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects*; D011189:Potassium Chloride / Q000494:pharmacology; D015742:Propofol / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D013552:Swine; D019789:Tetraethylammonium / Q000494:pharmacology; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*
D018686:Anesthetics, Intravenous; D002121:Calcium Channel Blockers; D016861:Cyclooxygenase Inhibitors; D004791:Enzyme Inhibitors; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D019335:Nitroarginine; D019789:Tetraethylammonium; D011189:Potassium Chloride; D015237:Dinoprost; D004110:Diltiazem; D005905:Glyburide; D007213:Indomethacin; D015742:Propofol