Studies on splenic contraction in cat

의학과/박사[한글] [영문] Accumulated evidences indicated that the administration of epinephrine causes a contraction of spleen in vivo or in vitro (Ahlquist et at. 1954, Bickerton, 1963). It has also been reported that the electrical stimulation of splanchnic nerve elicited the contraction of spleen (Gonda, 1965, Boatman et al. 1964).Saad(1935) extended previous observations and reported that epinephrine caused a contraction of isolated strips of spleen obtained from man, cat, guinea pig, rat and buffalo and further showed that epinephrine induced contractions could be abolished by ergotoxine. The present experiment was undertaken in an attempt to evaluate the nature of the adrenergic receptor involving the splenic contraction induced by catecholamines or by splanchnic nerve stimulation in cats. In addition, the influence of bretylium and reserpine on the splanchnic nerve stimulation were also examined. Healthy normal cats weighing approximately 3.0 kg of body weight were employed in this experiment. The splenic contraction was measured by the oncometer devised in this laboratory. The carotid arterial blood pressure was directly determined by mercury manometer. The splanchnic nerve stimulation was performed with a square-wave pulse of 5 second duration (5 volt, 20 cycle/sec) delivered from an electronic stimulator. 1. The intravenous administration of epinephrine or norepinephrine, and the stimulation of splanchnic nerve produced a sudden rise in the blood pressure and a marked contraction of spleen. 2. After pretreatment with bretylium, which blocks the release of catecholamines from their depots, the splanchinc nerve stimulation failed to produce its pressor and splenic contracting action. However, epinephrine or norepinephrine produced a marked rise in blood pressure and splenic contraction as usual. 3. In the cats pretreated with reserpine, which causes depletion of tissue catecholamines, the splanchnic nerve stimulation failed to produce splenic contraction and to rise in blood pressure. 4. Treatment with dibenzyline or dihydroergotamine, which is blocking agent of adrenergic alpha-re-cepter, completely abolished both pressor response and the splenic contraction elicited by catecholamines or by splanchnic nerve stimulation. 5. Treatment with dichloroisoproterenol, which specifically blocks the adrenergic beta-receptors failed to prevent the pressor response and splenic contraction caused by catecholamines or by splanchnic nerve stimulation. From the above results, it may be suggested that both pressor response and splenic contraction elicited by splanchnic nerve stimulation can be attributed to the released catecholamines, which act primarily on the adrenergic alpha-receptor proposed by Ahlquist(1948).restrictio