Effect of propofol on intracellular calcium ion concentration in isolated rabbit tracheal smooth muscle cells

Abstract

Objective To investigate the effect of propofol on the intracellular calcium ion concentration ([ Ca2+ ]i) in isolated rabbit tracheal smooth muscle cells (TSMCs).Methods The single rabbit TSMC was isolated by acute enzymatic isolation method as described by Cheng et al.The isolated TSMCs were randomly divided into 3 groups ( n =5 each):propofol group (group Ⅰ ),propofol + 2-aminoethoxy-diphenylborate (2-APB) group (group Ⅱ ) and propofol + the blocker ryanodine group (group Ⅲ).In group Ⅰ,the cells were incubated with propofol with the final concentration of 300 μmol/L for 15 min,followed by washing with calcium-free Hank's balanced salt solution (HBSS) for 3 times,acetylcholine 1 μmol/L was then added to the culture medium and [ Ca2+ ]i was recorded.In group Ⅱ,the cells were incubated with 2-APB with the final concentration of 40 μmol/L for 15 min,propofol with the final concentration of 300 μmol/L was then added,the cells were incubated with 2-APB and propofol for another 15 min,followed bywashing with calcium-free HBSS for 3 times,and acetylcholine 1 μmol/L was then added.In group Ⅲ,the cells were incubated with ryanodine with the final concentration of 10 μmol/L for 15 min,propofol with the final concentration of 300 μmol/L was then added,the cells were incubated with ryanodine and propofol for another 15 min,followed by washing with calcium-free HBSS for 3 times,and acetylcholine 1 μmol/L was then added.[ Ca2+ ]i in TSMCs was measured using the fluorescent Ca2+ indicator fluor-3/AM.Results Compared with group Ⅰ,no significant change was found in [Ca2+ ]i in group Ⅱ (P＞0.05),while [Ca2+ ]i was significantly decreased in group Ⅲ (P＜0.05).Conclusion Propofol can decrease the [Ca2+ ]i in isolated rabbit TSMCs,and the mechanism may be related to inhibition of inositol 1,4,5-trisphosphate pathway,but not ryanodine pathway. Key words: Propofol; Myocytes,smooth muscle; Trachea; Calcium; Ions