Sympathetic nerve activation decreases the release of vasoactive intestinal polypeptide from the feline intestine

The splanchnic nerves to the small intestine were stimulated in anaesthetized cats. Activation of the sympathetic nerves caused vasoconstriction, increased net fluid absorption and decreased release of vasoactive intestinal polypeptide (VIP) in the small intestine. In the colon, parasympathetic nerve stimulation elicited vasodilatation and increased release of VIP. Additional stimulation of the sympathetic lumbar colonic nerves decreased the colonic blood flow and inhibited the release of VIP. These effects of the stimulation of the lumbar colonic nerves were blocked by phentolamine. It is concluded that, in the feline intestine, sympathetic nerve stimulation presynaptically decreased the release of VIP via an alpha-adrenergic mechanism.