AJP - Gastrointestinal and Liver Physiology, Vol 253, Issue 1 13-G19, Copyright © 1987 by American Physiological Society
Corelease of PHI and VIP by vagal stimulation in the dog
A. Yasui, S. Naruse, C. Yanaihara, T. Ozaki, M. Hoshino, T. Mochizuki, E. E. Daniel and N. Yanaihara
Electrical vagal stimulation increased immunoreactive peptide histidine
isoleucine (IR-PHI) and vasoactive intestinal polypeptide (IR-VIP) levels
in the portal plasma in anesthetized dogs, depending on the stimulation
frequency. Atropine failed to suppress the vagal release of IR-PHI and
IR-VIP, whereas hexamethonium abolished the increase of both peptide
immunoreactivities. Gel filtration profiles of IR-PHI and IR-VIP in the
portal plasma obtained during vagal stimulation revealed major peaks of
IR-PHI and IR-VIP eluting in the same positions as synthetic PHI-27 and
VIP-28, respectively. These data demonstrate that PHI and VIP are
coreleased by vagal stimulation via a nicotinic ganglionic mechanism. An
additional peak of larger molecular weight IR-PHI was observed in gel
filtration of the portal plasma obtained under higher frequency vagal
stimulation, when measured by the N-terminal-specific PHI antiserum. The
presence of this larger form of IR-PHI together with a PHI-27-like
component was also demonstrated in tissue extracts of the entire length of
the gastrointestine, particularly in higher concentration in the stomach.
The structure and the physiological significance of this larger form of
IR-PHI remains to be elucidated.
