Control of movements of the stomach and spiral intestine of Raja and Scyliorhinus

Abstract

The extrinsic nerves of the stomach of dogfish and skates regulate the frequency and amplitude of contraction by inhibition followed by rebounds. By contrast the nerves of the spiral intestine are excitatory.Stimulation of the vagus nerve of the ray produced slight reduction in the amplitude of spontaneous contractions of the cardiac stomach. Much greater inhibition was produced by stimulation of the sympathetic nerves and was followed by large rebound contractions. These effects were imitated by adrenalin and serotonin which altered the frequency and amplitude of contraction in various ways. These actions were not blocked by either propranalol (1-5 x 10" 5 M) or phentolamine (2 x io~5 M) and indeed were often increased. The excitatory response to adrenalin was not blocked by TTX even after this had blocked the response to the nerve. Responses both to the nerve and adrenaline were blocked by trazodone. Acetyl choline caused some contraction of the stomach but only at high concentration. ATP gave responses similar to adrenalin but usually after long delay.Muscles of the spiral intestine of Raja or Scyliorhinus were activated by stimulation of their sympathetic nerves and by adrenalin. These responses were not blocked by phentolamine and only reduced by propranalol. They were blocked by trazodone. The response to adrenalin continued after the nerve was blocked by TTX. Acetyl choline had very little effect on the spiral intestine.The striking differences between the responses of the stomach and intestine are probably related to the fact that the plexus in the latter contains no nerve cells. The neurons in the stomach are therefore presumbly connected with the inhibition and large rebound contractions. I N T R O D U C T I O NLittle information is available about the movements of the gut of elasmobranchs. Some description was given recently of the stomach of the dogfish and skate (Young, 1980). The present paper provides information about the movements and pharmacology of the remarkable spiral intestine. It also gives a further study of the genesis of the inhibitory actions of the sympathetic nerves on the stomach and the rebound contractions that follow them.The spiral intestine is found in all elasmobranch fishes and in a few others such as Amia, Acipenser, Lepisosteus, Polypterus, Dipnoi and Latimeria. It is a compact roll of secretory and absorptive tissue, about 7 cm long in an adult skate of about 5 kg. When unrolled it shows a central axis to which is attached a continuous sheet about 40 cm long. This is fastened to the outer wall along a spiral track, giving about eight turns, closer together distally. This is an ingenious way of providing * Reprint requests should be sent to the Wellcome Institute.

Proceedings of the Physiological Society, 19‐20 September 1986, Oxford Meeting: Historical Demonstrations

“…More recent studies in the dogfish and skate (Young, 1980(Young, , 1983Andrews & Young, in preparation) have revealed that the control of gut motility mirrors in many ways the situation now known to occur in mammals. Various substances are now indicated as mediators of the effects of autonomic nerves in the elasmobranch gut, including acetylcholine, adrenaline, 5-hydroxytryptamine, ATP, substance P, bradykinin and members of the CCK family of peptides.…”

Proceedings of the Physiological Society, 22‐23 July 1988, Cambridge Meeting: Demonstrations

“…This system is not restricted to recordings of pH but may be used with any PVC membrane-based ISE. Studies in vivo and in vitro of elasmobranch gastric muscle recording tension, have revealed that splanchnic nerve (SPLN) stimulation can evoke contraction, inhibition and rebound (off) contractions depending upon stimulus frequency and gastric region (Young, 1980(Young, , 1983. Such studies have identified the overall effects of the SPLN but give little insight into contraction propagation or the relationships between activity in each region.…”

Primeiro registro de eversão vaginal em Psammobatis rutrum Jordan, 1891 (Rajiformes: Arhynchobatidae)

“…A externalização (protrusão) de órgãos internos em peixes tem sido registrada ao longo do tempo na literatura científica (Andrews & Bissell, 1934;Budker, 1971;Young, 1983;Moss, 1984;Crow & Brock, 1993;Morales & Dunker, 1999;Horodysky & Graves, 2005;Schaller & Dunker, 2005;Brunnschweiler, Nielsen & Motta, 2011;Wiersma, Verhoog, Fowler & Meekan, 2016;Weideli & Papastamatiou, 2021). Tais registros podem ser classificados em dois tipos distintos: 1.…”