[Effects of overexpression of beta2-adrenoceptor on contraction in cardiac myocytes isolated from failure hearts of rats].

Aim:To investigate the role of overexpression of β2-adrenoceptor on contraction in cardiac myocytes isolated from failure hearts of rats and primarily analyses its mechanisms.Methods:Primarily cultured cardiac myocytes were infected with adenovirus containing the sequence for human β2-adrenoceptors.The expression of β2-adrenoceptors was tested by Western blot.The contraction amplitudes induced by isoprenaline stimulation were measured.Results:Overexpression of β2-adrenoceptor increased the content in failure cardiac myocytes.The contraction amplitudes in failure cardiac myocytes were lower than that in the control(P0.01).Overexpression of β2-adrenoceptor improved the contraction of failure cardiac myocytes(P0.01,Failure+Adv.β2 group vs Failure group).Selective β2-adrenoceptor antagonist ICI 118,551 partially reversed the effects(P0.05,Failure+Adv.β2 +ICI group vs Failure +Adv.β2 group),but the contraction amplitudes in this Failure +Adv.β2 +ICI 118,551 group were still higher than that in only heart failure group(P0.05).Selective β1-adrenoceptor antagonist CGP20712A completely inhibited the effects of overexpression of β2-adrenoceptor on contraction amplitude in failure cardiac myocytes.Conclusion:Overexpression of β2-adrenoceptors improves the contraction of cardiac myocytes isolated from failure hearts of rats.The effect is related to β1-adrenoceptor.