Anesth Pain Med.  2011 Oct;6(4):336-341.

Mechanism of vasodilation by propofol in the rabbit renal artery

• Park SY
• Jung I
• Kwon SC

Abstract

BACKGROUND
Propofol directly inhibits vascular reactivity. However, available information regarding the underlying mechanisms of propofol is poor. Therefore, mechanisms of the underlying relaxant action of propofol were investigated using rabbit renal arteries.
METHODS
Propofol-induced relaxation of rabbit renal arteries was studied in contracted preparations with 50 mM KCl or 10microM histamine. Vessel tension was recorded with a pen recorder. We were interested in determining whether propofol-induced vasodilation is affected by endothelium-denudation, L-NG-nitroarginine methyl ester (L-NAME), tetraethylammonium (TEA), iberiotoxin, glibenclamide, 4-aminopyridine, 7-ethoxyresorufin, caffeic acid, baiclalein, ryanodine, and thapsigargin.
RESULTS
Propofol-induced concentration-dependent vasodilation was not affected either by endothelium denudation or by L-NAME during histamine-induced contraction. The relaxing effect of propofol on histamine-induced contraction was inhibited by either TEA, a K+ channel inhibitor, or iberiotoxin (100 nM), a selective blocker of the large conductance Ca(2+)-activated K+ channel (BKCa channel). In contrast, the relaxing effect of propofol was unaffected by 10microM glibenclamide, an ATP-sensitive K+ channel blocker, by 5 mM 4-aminopyridine, a blocker of delayed rectifier, by 7-ethoxyresorufin, a cytochrome P450 inhibitor, by 10microM caffeic acid and 10microM baiclalein, lipooxygenase inhibitors, or by 10microM ryanodine and thapsigargin, Ca2+store inhibitors.
CONCLUSIONS
These results suggest that the relaxant effect of propofol may result from activation of BKCa channels by inhibiting voltage-gated Ca2+ influx in a prolonged manner.

Keyword

Ca(2+)-activated K+ channel; Propofol; Renal artery; Vasodilation

MeSH Terms

4-Aminopyridine
Caffeic Acids
Contracts
Cytochrome P-450 Enzyme System
Endothelium
Glyburide
Glycosaminoglycans
Histamine
NG-Nitroarginine Methyl Ester
Oxazines
Peptides
Propofol
Relaxation
Renal Artery
Ryanodine
Tea
Tetraethylammonium
Thapsigargin
Vasodilation
4-Aminopyridine
Caffeic Acids
Cytochrome P-450 Enzyme System
Glyburide
Glycosaminoglycans
Histamine
NG-Nitroarginine Methyl Ester
Oxazines
Peptides
Propofol
Ryanodine
Tea
Tetraethylammonium
Thapsigargin