Summary
Eight smooth muscle preparations from the stomach, small intestine and large intestine of the guinea-pig were used to compare apamin's actions in reducing the effectiveness of transmission from enteric inhibitory nerves and in reducing responses to inhibitory agonists α,β-methylene ATP, VIP and isoprenaline. The effects of apamin on inhibitory reflexes in the ileum and colon were also evaluated. Apamin had little or no effect on responses to VIP and isoprenaline in any region, but consistently and substantially reduced responses to α,β-methylene ATP. Responses to stimulation of enteric inhibitory neurons were substantially reduced by apamin in the antrum circular muscle, ileum longitudinal and circular muscle, taenia coli and distal colon longitudinal muscle, but it was ineffective in the fundus circular muscle, proximal colon longitudinal muscle and distal colon circular muscle. It caused a small reduction of the relaxation of the ileal circular muscle caused reflexly by distension, but did not modify the similar descending inhibitory reflex in the circular muscle of the colon. It is concluded that apamin can be used to distinguish two types of non-noradrenergic transmission from enteric inhibitory nerves to gastrointestinal muscle. Furthermore, neither VIP nor ATP can be the sole transmitter chemical released from enteric inhibitory neurons throughout the gastrointestinal tract.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Beani L, Bianchi C, Crema A (1971) Vagal non-adrenergic inhibition of guinea-pig stomach. J Physiol (Lond) 217:259–279
Burnstock G (1972) Purinergic nerves. Pharmac Rev 24:509–581
Burnstock G (1981) Neurotransmitters and trophic factors in the autonomic nervous system. J Physiol (Lond) 313:1–35
Burnstock G, Campbell G, Rand MJ (1966) The inhibitory innervation of the taenia of the guinea-pig caecum. J Physiol (Lond) 182:504–526
Campbell G (1966) The inhibitory nerve fibres in the vagal supply to the guinea-pig stomach. J Physiol (Lond) 185:600–612
Cocks T, Burnstock G (1979) Effects of neuronal polypeptides on intestinal smooth muscle. A comparison with non-adrenergic, non-cholinergic nerve stimulation and ATP. Eur J Pharmacol 54:251–259
Costa M, Furness JB (1976) The peristaltic reflex: An analysis of the nerve pathways and their pharmacology. Naunyn-Schmiedeberg's Arch Pharmacol 294:47–60
Costa M, Furness JB (1982) Nervous control of intestinal motility. Handbook Exp Pharmacol 59:279–382
Fahrenkrug J (1979) Vasoactive intestinal polypeptide: Measurement, distribution and putative neurotransmitter function. Digestion 19:149–169
Frew R, Lundy PM (1982a) Evidence against ATP being the nonadrenergic, non-cholinergic inhibitory transmitter in the guinea-pig stomach. Eur J Pharmacol 81:333–336
Frew R, Lundy PM (1982b) Effect of arylazido aminopropionyl ATP (ANAPP3), a putative ATP antagonist, on ATP responses of guinea-pig smooth muscle. Life Sci 30:259–267
Furness JB (1969) An electrophysiological study of the innervation of the smooth muscle of the colon. J Physiol 205:549–562
Furness JB, Costa M (1973) The nervous release and the action of substances which affect intestinal smooth muscle through neither adrenoceptors nor cholinoceptors. Phil Trans R Soc Lond B 265:123–133
Hirst GDS, Holman ME, McKirdy HC (1975) Two descending nerve pathways activated by distension of guinea-pig small intestine. J Physiol 244:113–127
Maas AJJ (1981) The effect of apamin on response evoked by field stimulation in guinea-pig taenia caeci. Eur J Pharmacol 73:1–9
Mass AJJ, den Hertog A (1979) The effect of apamin on the smooth muscle cells of guinea-pig taenia coli. Eur J Pharmacol 58:151–156
Maas AJJ, den Hertog A, Ra R, van den Akker J (1980) The action of apamin on guinea-pig taenia caeci. Eur J Pharmacol 67:265–274
Mackenzie I, Burnstock G (1980) Evidence against vasoactive intestinal polypeptide being the non-adrenergic, non-cholinergic inhibitory transmitter released from nerves supplying the smooth muscle of the guinea-pig taenia coli. Eur J Parmacol 67:255–264
Makhlouf GM (1985) Enteric neuropeptides: role in neuromuscular activity of the gut. Trends Pharmacol Sci 6:214–218
Martinson J (1965) Studies on the efferent vagal control of the stomach. Acta Physiol Scand 65, Suppl 255:1–24
Niel JP, Bywater RAR, Taylor GS (1983) Apamin resistant poststimulus hyperpolarization in the circular muscle of the guinea-pig ileum. J Autonomic Nervous System 9:565–569
Smith IK, Bywater RAR (1983) Apamin resistant hyperpolarization and noncholinergic excitation in the guinea-pig distal colon. Neurosci Letts Supplement 11:575
Vladimirova IA, Shuba MF (1978) Strychnine, hydrastine and apamin effect on synaptic transmission in smooth muscle cells. Neurofiziologia 10:295–300
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Costa, M., Furness, J.B. & Humphreys, C.M.S. Apamin distinguishes two types of relaxation mediated by enteric nerves in the guinea-pig gastrointestinal tract. Naunyn-Schmiedeberg's Arch. Pharmacol. 332, 79–88 (1986). https://doi.org/10.1007/BF00633202
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00633202