Leukocyte mobilization from the guinea pig spleen by muscarinic cholinergic stimulation

Important interactions between the immune system and the nervous and endocrine systems have become increasingly accepted. The present results demonstrate that the cholinergic agonist carbacholine greatly increased the number of granulocytes and lymphocytes in the splenic venous blood, but not arterial blood, shortly after administration to guinea pigs. The effect was largely blocked by pretreatment with atropine. In contrast, animals treated with indomethacin had a decreased number of leukocytes in both splenic venous and arterial blood. A decrease in relative splenic weight due to carbacholine treatment was also blocked by atropine. However, cholinergic leukocyte mobilization, or that previously observed after adrenergic stimulation, may not be caused by capsule contraction since it is not accompanied by mobilization of erythrocytes. Furthermore, indomethacin, which potentiates the response of splenic smooth muscle to adrenergic stimuli, blocked the effect of noradrenaline (NA) on leukocyte mobilization.