Abstract
This study combined immunohistochemical double-labeling techniques with functional studies to characterize the neurokinin-1 (NK1) receptors mediating neuronal and vasodilator responses in submucosal guinea pig ileum. NK1 receptor distribution in whole mount preparations of the submucosa was examined using a rabbit polyclonal antibody directed against the COOH terminus of the rat NK1 receptor. Results showed that 97% of neuropeptide Y immunoreactive submucosal neurons colocalized NK1 receptor immunoreactivity, whereas vasoactive intestinal polypeptide immunoreactive neurons were not NK1 immunoreactive. Intracellular recordings were made using neurobiotin- filled electrodes to enable reidentification of recorded neurons for immunohistochemical study. The selective NK1 agonists [Sar9,Met(O2)11]substance P (SP) and septide depolarized S-type submucosal neurons. Of these neurons, 36% were NK1 immunoreactive and 64% were not. NK1 immunoreactivity was not observed on submucosal arterioles, but superfusion of [Sar9,Met(O2)11]SP and septide dilated preconstricted submucosal arterioles. Agonist-evoked responses in both neurons and blood vessels were blocked by the selective NK1 antagonist CP-99994. These findings suggest that NK1 receptors are found on submucosal neurons and arterioles and that electrophysiological and immunohistochemical techniques may identify conformational variants of the receptor.
Original language | English (US) |
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Pages (from-to) | G670-G678 |
Journal | American Journal of Physiology - Gastrointestinal and Liver Physiology |
Volume | 273 |
Issue number | 3 36-3 |
DOIs | |
State | Published - Sep 1997 |
Keywords
- Blood flow
- Secretion
- Substance P
- Tachykinin receptors
ASJC Scopus subject areas
- Physiology
- Hepatology
- Gastroenterology
- Physiology (medical)