TY - JOUR

T1 - Thapsigargin, a new calcium-dependent epithelial anion secretagogue

AU - Brayden, D J

AU - Hanley, M R

AU - Thastrup, Ole

AU - Cuthbert, A W

PY - 1989

Y1 - 1989

N2 - 1. Thapsigargin, a sesquiterpene lactone, was shown to cause electrogenic anion secretion in monolayers of human colonic epithelial cells, an effect which was crucially dependent upon calcium and did not involve eicosanoid formation. 2. To measure the secretory effect calcium needed to be present in the external bathing solution. By means of Fura-2 fluorescence measurements thapsigargin was shown to raise Cai by around 250 nM when the bathing solution contained calcium. In the nominal absence of external calcium thapsigargin raised Cai by only 60 nM, but from a lower basal value. This was insufficient to cause secretion. 3. Effects of other calcium-dependent secretagogues (e.g. lysylbradykinin) were inhibited in the presence of thapsigargin, whereas kinin responses were potentiated if the peptide was added following a stimulus which increases cyclic AMP. 4. From the data given here and the known behaviour of colonic epithelia it is concluded that thapsigargin increases Cai by a non-ionophoric mechanism by release from internal stores. Calcium-stimulated calcium influx then follows resulting in the opening of basolateral K channels, increasing the electrochemical gradient for chloride efflux, or alternatively by activating anion channels in the apical membrane. It is concluded that thapsigargin is a potentially important tool for examining epithelial mechanisms.

AB - 1. Thapsigargin, a sesquiterpene lactone, was shown to cause electrogenic anion secretion in monolayers of human colonic epithelial cells, an effect which was crucially dependent upon calcium and did not involve eicosanoid formation. 2. To measure the secretory effect calcium needed to be present in the external bathing solution. By means of Fura-2 fluorescence measurements thapsigargin was shown to raise Cai by around 250 nM when the bathing solution contained calcium. In the nominal absence of external calcium thapsigargin raised Cai by only 60 nM, but from a lower basal value. This was insufficient to cause secretion. 3. Effects of other calcium-dependent secretagogues (e.g. lysylbradykinin) were inhibited in the presence of thapsigargin, whereas kinin responses were potentiated if the peptide was added following a stimulus which increases cyclic AMP. 4. From the data given here and the known behaviour of colonic epithelia it is concluded that thapsigargin increases Cai by a non-ionophoric mechanism by release from internal stores. Calcium-stimulated calcium influx then follows resulting in the opening of basolateral K channels, increasing the electrochemical gradient for chloride efflux, or alternatively by activating anion channels in the apical membrane. It is concluded that thapsigargin is a potentially important tool for examining epithelial mechanisms.

KW - Adenocarcinoma

KW - Anions

KW - Calcimycin

KW - Calcium

KW - Colonic Neoplasms

KW - Electrophysiology

KW - Epithelium

KW - Forskolin

KW - Humans

KW - Plant Extracts

KW - Thapsigargin

KW - Tumor Cells, Cultured

M3 - Journal article

C2 - 2511993

VL - 98

SP - 809

EP - 816

JO - British Journal of Pharmacology

JF - British Journal of Pharmacology

SN - 0007-1188

IS - 3

ER -