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Inhibitory neuropeptides and intrinsic inhibitory innervation of descending human colon

Authors :
Vay Liang W. Go
Joseph H. Szurszewski
J. Aidan Carney
Timothy R. Koch
Source :
Digestive Diseases and Sciences. 36:712-718
Publication Year :
1991
Publisher :
Springer Science and Business Media LLC, 1991.

Abstract

The effects of aging on inhibitory neuropeptide concentrations and intrinsic inhibitory innervation of circular muscle were investigated using normal descending colon obtained at surgery. Immunoreactive vasoactive intestinal peptide, peptide histidine-methionine, met5-enkephalin, neuropeptide Y, and somatostatin were extracted from specimens of muscularis externa (patient ages: 19-84 years) and measured by radioimmunoassay. Intracellular electrical activity was recorded from strips of circular muscle (patients ages: 49-84 years) using glass microelectrodes; inhibitory junction potentials were evoked by electrical field stimulation. There were no significant differences (t tests: P greater than 0.05) between neuropeptide concentrations in patients less than 70 years old (N = 28) compared to patients greater than or equal to 70 years old (N = 12). However, the amplitude of inhibitory junction potentials declined with increasing patient age (r = -0.58, P = 0.02, N = 16), with no change in resting membrane potentials (r = 0.22; P greater than 0.05). The decline in amplitude in women (r = -0.68, P = 0.03, N = 9) preceded the decline in men (r = -0.62, P = 0.10, N = 7). Age-related decline in inhibitory junction potentials could be related to decreased: density of inhibitory nerves, release of inhibitory neurotransmitter, density of binding sites for inhibitory neurotransmitter on smooth muscle, or a combination thereof. Alternatively, this decline might represent a change in interaction of inhibitory neurotransmitter with the smooth muscle membrane, such as a change in coupling of binding site with the potassium channel, decreased number of potassium channels, or altered permeability of the potassium channel.

Details

ISSN :
15732568 and 01632116
Volume :
36
Database :
OpenAIRE
Journal :
Digestive Diseases and Sciences
Accession number :
edsair.doi.dedup.....71ae25471e49a3fbf5ffbde64a3b82d5