TY - JOUR

T1 - Ca2+ influx induced by the Ca2+-ATPase inhibitors 2,5-di-(t-butyl)-1,4-benzohydroquinone and thapsigargin in bovine adrenal chromaffin cells

AU - Robinson, I. M.

AU - Cheek, T. R.

AU - Burgoyne, R. D.

PY - 1992/12/31

Y1 - 1992/12/31

N2 - We have characterized the effect of the Ca2+-ATPase inhibitors 2,5-di-(t-butyl)-1,4-benzohydroquinone (tBHQ) and thapsigargin on the concentration of cytosolic Ca2+ in single bovine adrenal chromaffin cells by video-imaging of fura-2-loaded cells. Addition of either inhibitor released Ca2+ from internal stores in the absence of external Ca2+ tBHQ was unable to stimulate further Ca2+ release after addition of thapsigargin, but thapsigargin could do so after release by tBHQ, indicating that the tBHQ-sensitive stores are a sub-set of those sensitive to thapsigargin. Angiotensin II was able to elicit Ca2+ release after application of tBHQ, indicating that at least part of the tBHQ-sensitive stores were distinct from those discharged by Ins(1,4,5)P3. In the presence of external Ca2+, both Ca2+-ATPase inhibitors produced a more prolonged rise in cytosolic Ca2+ consistent with stimulated Ca2+ entry. The ability of the inhibitors to activate a Ca2+-entry pathway was confirmed by monitoring quenching of fura-2 after stimulated entry of the Ca2+ surrogate Mn2+. These findings indicate that bovine adrenal chromaffin cells possess a mechanism by which Ca2+ entry can be activated. following emptying of certain internal stores, independently of receptor occupation.

AB - We have characterized the effect of the Ca2+-ATPase inhibitors 2,5-di-(t-butyl)-1,4-benzohydroquinone (tBHQ) and thapsigargin on the concentration of cytosolic Ca2+ in single bovine adrenal chromaffin cells by video-imaging of fura-2-loaded cells. Addition of either inhibitor released Ca2+ from internal stores in the absence of external Ca2+ tBHQ was unable to stimulate further Ca2+ release after addition of thapsigargin, but thapsigargin could do so after release by tBHQ, indicating that the tBHQ-sensitive stores are a sub-set of those sensitive to thapsigargin. Angiotensin II was able to elicit Ca2+ release after application of tBHQ, indicating that at least part of the tBHQ-sensitive stores were distinct from those discharged by Ins(1,4,5)P3. In the presence of external Ca2+, both Ca2+-ATPase inhibitors produced a more prolonged rise in cytosolic Ca2+ consistent with stimulated Ca2+ entry. The ability of the inhibitors to activate a Ca2+-entry pathway was confirmed by monitoring quenching of fura-2 after stimulated entry of the Ca2+ surrogate Mn2+. These findings indicate that bovine adrenal chromaffin cells possess a mechanism by which Ca2+ entry can be activated. following emptying of certain internal stores, independently of receptor occupation.

U2 - 10.1042/bj2880457

DO - 10.1042/bj2880457

M3 - Journal article

AN - SCOPUS:0026470008

VL - 288

SP - 457

EP - 463

JO - Biochemical Journal

JF - Biochemical Journal

SN - 0264-6021

IS - 2

ER -