Modulation of cholinergic neurotransmitter release from myenteric plexus by somatostatin.
Efflux of radiolabeled acetylcholine (Ach) was studied in vitro using myenteric plexus-longitudinal muscle strips from guinea pig small intestine. The data showed that somatostatin (6.0 x 10(-7) M) depressed resting output of Ach from enteric neurons and this inhibition was unaltered in the presence of naloxone (1.0 x 10(-6) M). The inhibition by somatostatin on field-stimulated Ach release was dose-dependent but this inhibition was never complete; there was a 40% fraction of total release remained resistant to somatostatin. Both caerulein (2.85 x 10(-9) M) and guanidine (3.0 x 10(-3) M) stimulated release of [H3]-Ach from plexus neurons. The release of Ach induced by guanidine or caerulein was also susceptible to inhibition by somatostatin (6.0 x 10(-7) M). This study provides functional evidence to further substantiate an inhibitory action on plexus cholinergic neurons by somatostatin.
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D002108:Ceruletide / Q000494:pharmacology; D004558:Electric Stimulation; D005260:Female; D019791:Guanidine; D006146:Guanidines / Q000494:pharmacology; D006168:Guinea Pigs; D009197:Myenteric Plexus / Q000187:drug effects / Q000378:metabolism*; D009270:Naloxone / Q000494:pharmacology; D018377:Neurotransmitter Agents / Q000378:metabolism*; D010275:Parasympathetic Nervous System / Q000187:drug effects / Q000378:metabolism*; D013004:Somatostatin / Q000494:pharmacology*; D013997:Time Factors
D006146:Guanidines; D018377:Neurotransmitter Agents; D009270:Naloxone; D013004:Somatostatin; D002108:Ceruletide; D019791:Guanidine; D000109:Acetylcholine