Sympathetic innervation of the spleen of the cane toad, bufo marinus

Abstract

1. The sympathetic nervous supply to the toad spleen was studied using perfused spleen preparations, isolated spleen strips and Falck-Hillarp flourescent histochemistry. 2. The order of potency for adrenergic agonists indicates an alpha adrenoceptor mediated constriction of the spleen. 3. Acetylcholine gives variable reponses on the perfused spleen, but contracts the isolated spleen strips. The effect of acetylcholine appears to be via muscarinic receptors, although no quantitative analysis could be made. 4. The constrictory innervation of the spleen appears to be solely adrenergic, and fluorescent histochemistry reveals fibres mainly around intrasplenic blood vessels and in the capsule. No evidence for a cholinergic innervation was obtained. 5. The sympathetic innervation of the spleen leaves the spinal chord in the ventral roots of the spinal nerves, and pre-synaptic fibres run to the coeliac ganglion. The vast majority of fibres to the spleen appear to have their cell bodies in the coeliac ganglion, since d-tubocurarine inhibits the effects of nerve stimulation proximal, but not distal, to this ganglion.