Calcitonin gene-related peptide inhibits nonadrenergic noncholinergic contraction of guinea pig distal colon.
In the guinea pig distal colon, calcitonin gene-related peptide (CGRP, 0.1-30 nM) produced a concentration-dependent inhibition in electrically-evoked nonadrenergic noncholinergic (NANC) contractions and exogenous substance P-induced contractions. Both the inhibitory actions of CGRP were insensitive to human CGRP(8-37) (1-3 microM), a CGRP1 receptor antagonist. These results indicate that in the distal colon, CGRP inhibits electrically-evoked NANC contraction through a postjunctional mechanism, in contrast to our previously described results that CGRP enhances the NANC contraction of guinea pig proximal colon via a prejunctional mechanism.
Kojima
S
S
Department of Pharmacology, Dokkyo University School of Medicine, Tochigi, Japan.
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000008:administration & dosage / Q000494:pharmacology*; D000077221:Calcitonin Gene-Related Peptide Receptor Antagonists; D003106:Colon / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D017629:Gap Junctions / Q000187:drug effects; D006168:Guinea Pigs; D006801:Humans; D008297:Male; D008916:Miotics / Q000008:administration & dosage / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D010446:Peptide Fragments / Q000008:administration & dosage / Q000494:pharmacology*; D013373:Substance P / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects
D000077221:Calcitonin Gene-Related Peptide Receptor Antagonists; D008916:Miotics; D010446:Peptide Fragments; C058636:calcitonin gene-related peptide (8-37); D013373:Substance P; D015740:Calcitonin Gene-Related Peptide