Effect of galanin on the opossium lower esophageal sphincter

Selective regional vasoconstriction underlying pressor effects of galanin in anaesthetized possums compared with cats.

“…In mammalian nonvascular smooth muscle too, galanin can be a potent constrictor (e.g. rat jejunal longitudinal muscle: Ekblad et al 1985; opossum lower oesophageal sphincter: Rattan & Goyal, 1987). It appears that constriction of smooth muscle by galanin as demonstrated in the possum is, in fact, not uncommon throughout the vertebrates.…”

“…In an earlier study investigating the interaction between cardiac sympathetic and vagal nerves in the possum (Courtice, Potter & McCloskey, 1993) we observed a strong pressor response to galanin, a result which was in contrast to most other mammalian species. Interestingly, a pressor response to galanin has been reported in one other mammal, an American marsupial, the opossum Didelphis virginiana (Rattan & Goyal, 1987). In the present study, we investigate the underlying causes of the pressor effect in the brush-tailed possum compared with the depressor effect in the cat, by establishing the regional vascular responses to galanin in each species.…”

Occurrence, Distribution and Motor Effects of Galanin in the Porcine Lower Esophageal Sphincter

“…The reason why no effect of slow intra-arterial infusion of up to 100 pmol galanin/kg/min was observed must await further studies on galanin receptor properties and local rate of metabolism. In the opossum esophagus, and inhibitory noncholinergic, nonadrenergic transmitter role of galanin is unlikely [10], and vagally me diated esophageal peristalsis and LES relax ation are inhibited by galanin, probably by selective inhibition of release of noncholinergic neurotransmitters [9,10]. The effect of vagal activation is species-specific, and the vagally mediated LES contraction in the pig was not influenced by galanin infusion in our experience.…”

“…This localization of GAL-LI is the same as in the rat and mouse esophagus [7], and a still more widespread distribution has been demonstrated in the opossum esophagus [8], We observed a dosedependent increase in LESP in response to close intra-arterial bolus injection of galanin. Others have shown that the contractile mechanism in the rat intestine [3] and opos sum esophagus [10] is a direct action on the smoothe muscle. The reason why no effect of slow intra-arterial infusion of up to 100 pmol galanin/kg/min was observed must await further studies on galanin receptor properties and local rate of metabolism.…”

“…In the esophagus, GAL-LI has been demonstrated in the rat, mouse and opossum [7,8], whereas no GAL-LI was found in the guinea pig [7], The effect of galanin on esophageal motility has been studied in the opossum. Galanin inhibited peristalsis [9], produced lower esophageal sphincter (LES) contrac tion, and suppressed LES relaxation [10]. The aim of this investigation was to examine the cellular localization and topographical distribution of galanin in the porcine esoph agus, and to examine the effect of galanin on resting LES tone and vagally mediated LES contraction.…”