Elevation of adenosine 3',5'-phosphate mimics slow synaptic excitation in myenteric neurones of the guinea-pig

• Published in: The Journal of physiology Vol. 376; no. 1; pp. 451 - 460
• Main Authors: Palmer, J M, Wood, J D, Zafirov, D H
• Format: Journal Article
• Language: English
• Published: Oxford The Physiological Society 01-07-1986; Blackwell
• Subjects: 1-Methyl-3-isobutylxanthine - pharmacology; Action Potentials - drug effects; Animals; Biological and medical sciences; Cyclic AMP - analogs & derivatives; Cyclic AMP - pharmacology; Fundamental and applied biological sciences. Psychology; Guinea Pigs; In Vitro Techniques; Intestine, Small - innervation; Intestine. Mesentery; Myenteric Plexus - cytology; Myenteric Plexus - physiology; Neurons - drug effects; Synapses - physiology; Time Factors; Vertebrates: digestive system; Nervous plexus; Digestive system; Rodentia; Electrophysiology; Small intestine; Auerbach plexus; Vertebrata; Mammalia; Guinea pig; Cyclic nucleotide; AMP-3',5'; Excitatory postsynaptic potential; Sympathic nervous system
• ISSN: 0022-3751; 1469-7793
• DOI: 10.1113/jphysiol.1986.sp016163

Intracellular recording was used to assess the effects of elevation of intraneuronal adenosine 3',5'-phosphate (cyclic AMP)
on electrical behaviour of AH/Type 2 myenteric neurones in guinea-pig small intestine. Intracellular injection of cyclic AMP
resulted in membrane depolarization, increased input resistance, suppression of post-spike hyperpolarizing potentials and
enhanced excitability. Application of 8-(4-chlorophenylthio) cyclic AMP or 8-bromo cyclic AMP, which are membrane permeant
analogues of cyclic AMP, resulted in the same changes in electrical behaviour as intracellular injection of cyclic AMP. Treatment
with the phosphodiesterase inhibitor, 3-isobutyl-l-methylxanthine, resulted in the same changes in neuronal electrical behaviour
as intracellular injection of cyclic AMP and application of permeable analogues of cyclic AMP. Each of the treatments, which
were expected to elevate intraneuronal cyclic AMP, duplicated the electrophysiological behaviour of AH/Type 2 neurones during
slow synaptic excitation. The results support the hypothesis that the biochemical basis for slow synaptic excitation in AH/Type
2 myenteric neurones of guinea-pig small intestine is increased synthesis of cyclic AMP in the cell soma.