EFFECTS OF CLONIDINE ON MYOCARDIAL Gsα mRNA EXPRESSION AFTER SCALDS IN RATS

AIMTo explore the role of clonidine (Clo) on myocardial Gsα mRNA expression after scalds in rats. METHODSA 30% skin-full-thickness scald was produced by immersing rats in 95℃ water for 10 s. The myocardial Gsα mRNA expression level, cyclic AMP content and adenylyl cyclase (AC) activity were determined with dot blotting hybridization, in situ hybridization, radioimmunoassay and indirect method. RESULTSThree hours after scalds, the myocardial Gsα mRNA was significantly decreased to (61±20)% of the control group (P<0.01). AC activity and cAMP content were also decreased. Clo (0.3, 1.0 and 3.0 mg·kg^-1, ip) was shown to increase myocardial Gsα mRNA expression level (P<0.01 or P<0.05) after scalds to (131±28)%, (142±51)% and (139±48)% of the scald group, respectively, which were correlated with the Clo dose (γ=0.597, P<0.05). Clo 1.0 mg·kg^-1 and 3.0 mg·kg^-1 (ip) promoted AC activity and increased cAMP content, but Clo 0.3 and 0.1 mg·kg^-1 showed no significant effect (P>0.05). Selective I₁-imidazoline receptor antagonist efaroxan (Efa) (10, 5 mg·kg^-1, ip) was found to partially reverse the effect of Clo, while Efa 2.5 mg·kg^-1 showed no significantly influence. The reduced quantity of Gsα mRNA expression level correlated well with the Efa dose (γ=0.900, P<0.05). The change of AC and cAMP was similar to Gsα mRNA. CONCLUSIONClo increased the myocardial Gsα mRNA expression, AC activity and cAMP content after scalds in rats.