BACKGROUND & AIMS: This study has investigated stimulus-secretion coupling of enterochromaffin cells by studying the cellular location and function of voltage-gated Ca(2+) channels within small intestinal crypts. METHODS: Digital fluorescence imaging and electrochemical detection were used to measure intracellular Ca(2+) responses and serotonin (5-hydroxytryptamine [5-HT]) secretion in intact crypts isolated from guinea pig and human duodenum. RESULTS: In fluo-3-loaded crypts, electrical depolarization with high K(+) solution increased cytosolic free [Ca(2+)] only in single cells subsequently identified by immunocytochemistry as enterochromaffin cells. In guinea pig enterochromaffin cells, the L-type Ca(2+) channel agonist FPL 64176 (3 micromol/L) did not change resting intracellular [Ca(2+)] but potentiated the depolarization-evoked increase in [Ca(2+)] (298 +/- 72 nmol/L) by 19 +/- 3-fold. In the majority of human enterochromaffin cells, FPL 64176 alone increased resting [Ca(2+)] by 423 +/- 171 nmol/L. Secretion studies in guinea pig crypts showed that high K(+) and FPL 64176 caused a 12-fold increase in 5-HT release. Noradrenaline caused increases in both enterochromaffin cell [Ca(2+)] and 5-HT release. CONCLUSIONS: Using this approach, we have found that in duodenal crypts, enterochromaffin cells, but not other epithelial cells, contain L-type voltage-gated Ca(2+) channels involved in regulating 5-HT secretion. These data have implications for the pharmacological control of intestinal disorders involving enterochromaffin cell dysfunction.
BACKGROUND & AIMS: This study has investigated stimulus-secretion coupling of enterochromaffin cells by studying the cellular location and function of voltage-gated Ca(2+) channels within small intestinal crypts. METHODS: Digital fluorescence imaging and electrochemical detection were used to measure intracellular Ca(2+) responses and serotonin (5-hydroxytryptamine [5-HT]) secretion in intact crypts isolated from guinea pig and human duodenum. RESULTS: In fluo-3-loaded crypts, electrical depolarization with high K(+) solution increased cytosolic free [Ca(2+)] only in single cells subsequently identified by immunocytochemistry as enterochromaffin cells. In guinea pig enterochromaffin cells, the L-type Ca(2+) channel agonist FPL 64176 (3 micromol/L) did not change resting intracellular [Ca(2+)] but potentiated the depolarization-evoked increase in [Ca(2+)] (298 +/- 72 nmol/L) by 19 +/- 3-fold. In the majority of human enterochromaffin cells, FPL 64176 alone increased resting [Ca(2+)] by 423 +/- 171 nmol/L. Secretion studies in guinea pig crypts showed that high K(+) and FPL 64176 caused a 12-fold increase in 5-HT release. Noradrenaline caused increases in both enterochromaffin cell [Ca(2+)] and 5-HT release. CONCLUSIONS: Using this approach, we have found that in duodenal crypts, enterochromaffin cells, but not other epithelial cells, contain L-type voltage-gated Ca(2+) channels involved in regulating 5-HT secretion. These data have implications for the pharmacological control of intestinal disorders involving enterochromaffin cell dysfunction.
Authors: Fan Wang; Kaitlyn Knutson; Constanza Alcaino; David R Linden; Simon J Gibbons; Purna Kashyap; Madhusudan Grover; Richard Oeckler; Philip A Gottlieb; Hui Joyce Li; Andrew B Leiter; Gianrico Farrugia; Arthur Beyder Journal: J Physiol Date: 2016-08-13 Impact factor: 5.182
Authors: Ravinarayan Raghupathi; Michael D Duffield; Leah Zelkas; Adrian Meedeniya; Simon J H Brookes; Tiong Cheng Sia; David A Wattchow; Nick J Spencer; Damien J Keating Journal: J Physiol Date: 2013-10-07 Impact factor: 5.182