[Changes in the beta-receptor density and its responsiveness to beta-agonist in rabbit myocardium during hemorrhagic...

We studied change of the beta-receptor density and its responsiveness to beta-agonist in rabbit myocardium during hemorrhagic shock. We found that down-regulation of beta-receptor in the myocardium appears after hemorrhagic shock of approximately 180 minutes and inversely, defense mechanism of the organism comes in by increasing its the affinity. With regard to the responsiveness of beta-agonist, decrease in the elevating rate of cyclic adenosine monophosphate (c-AMP) was already recognized after 30 minutes of the hemorrhagic shock, and not only c-AMP, but also functional decrease of the response was recognized after 180 minutes. The results suggest that beta-adrenergic system can not function because of remarkable metabolic acidosis if the hemorrhagic shock is left untreated for from 30 to 180 minutes.