Diadenosine polyphosphates regulate cytosolic calcium in human fibroblast cells by interaction with P2x purinoceptors coupled to phospholipase C

TY - JOUR

T1 - Diadenosine polyphosphates regulate cytosolic calcium in human fibroblast cells by interaction with P2x purinoceptors coupled to phospholipase C

AU - Tepel, M

AU - Löwe, S

AU - Nofer, J R

AU - Assmann, G

AU - Schlüter, H

AU - Zidek, W

PY - 1996/6/13

Y1 - 1996/6/13

N2 - The effects of diadenosine pentaphosphate (AP5A), and diadenosine hexaphosphate (AP6A) on the cytosolic-free Ca2+ concentration ([Ca2+]i) were evaluated in cultured human fibroblast cells (HF cells) using the fluorescent dye technique. AP5A, and AP6A concentration-dependently increased [Ca2+]i in HF cells. The addition of 10 mumol/1 AP5A and AP6A significantly increased [Ca2+]i in HF cells from 71 +/- 3 nmol/1 (n = 184) to 241 +/- 39 nmol/1 (n = 11; P < 0.001 compared to resting value) and to 227 +/- 26 nmol/1 (n = 23; P < 0.001), respectively. The purinoceptor P2 blockers, suramin and pyridoxal-phosphate-6-azophenyl-2',4'-disulphonic acid (PPADS), inhibited the diadenosine polyphophate-induced [Ca2+]i increase, whereas the P2y purinoceptor blocker, reactive blue, had no effect. Adenosinetriphosphate (ATP) and the P2x agonist, alpha 1 beta-methylene-ATP also significantly increased [Ca2+]i in HF cells, whereas the P2y agonist methylthio-ATP showed only a small [Ca2+]i response. Diadenosine polyphosphates mainly induced transplasmamembrane Ca2+ influx as was confirmed by experiments in the absence of extracellular Ca2+ or by manganese quenching studies. Organic (verapamil) and inorganic Ca2+ channel blockers (NiCI2) significantly reduced the AP6A induced transplasmamembrane Ca2+ influx. The inhibitor of phosphatidylcholine-specific phospholipase C, D609, significantly reduced the effect of diadenosine polyphosphates on [Ca2+]i in HF cells. It is concluded that diadenosine polyphosphates regulate transplasmamembrane Ca2+ influx after occupation of P2x receptors via activation of phosphatidylcholine-specific phospholipase C and hence of voltage-operated Ca2+ channels.

AB - The effects of diadenosine pentaphosphate (AP5A), and diadenosine hexaphosphate (AP6A) on the cytosolic-free Ca2+ concentration ([Ca2+]i) were evaluated in cultured human fibroblast cells (HF cells) using the fluorescent dye technique. AP5A, and AP6A concentration-dependently increased [Ca2+]i in HF cells. The addition of 10 mumol/1 AP5A and AP6A significantly increased [Ca2+]i in HF cells from 71 +/- 3 nmol/1 (n = 184) to 241 +/- 39 nmol/1 (n = 11; P < 0.001 compared to resting value) and to 227 +/- 26 nmol/1 (n = 23; P < 0.001), respectively. The purinoceptor P2 blockers, suramin and pyridoxal-phosphate-6-azophenyl-2',4'-disulphonic acid (PPADS), inhibited the diadenosine polyphophate-induced [Ca2+]i increase, whereas the P2y purinoceptor blocker, reactive blue, had no effect. Adenosinetriphosphate (ATP) and the P2x agonist, alpha 1 beta-methylene-ATP also significantly increased [Ca2+]i in HF cells, whereas the P2y agonist methylthio-ATP showed only a small [Ca2+]i response. Diadenosine polyphosphates mainly induced transplasmamembrane Ca2+ influx as was confirmed by experiments in the absence of extracellular Ca2+ or by manganese quenching studies. Organic (verapamil) and inorganic Ca2+ channel blockers (NiCI2) significantly reduced the AP6A induced transplasmamembrane Ca2+ influx. The inhibitor of phosphatidylcholine-specific phospholipase C, D609, significantly reduced the effect of diadenosine polyphosphates on [Ca2+]i in HF cells. It is concluded that diadenosine polyphosphates regulate transplasmamembrane Ca2+ influx after occupation of P2x receptors via activation of phosphatidylcholine-specific phospholipase C and hence of voltage-operated Ca2+ channels.

KW - Bridged-Ring Compounds

KW - Calcium

KW - Calcium Channel Blockers

KW - Cells, Cultured

KW - Cytosol

KW - Dinucleoside Phosphates

KW - Fibroblasts

KW - Fura-2

KW - Humans

KW - Manganese

KW - Nickel

KW - Phosphodiesterase Inhibitors

KW - Purinergic Antagonists

KW - Receptors, Purinergic

KW - Suramin

KW - Theobromine

KW - Thiones

KW - Type C Phospholipases

KW - Vasoconstrictor Agents

KW - Verapamil

KW - Xanthines

KW - Journal Article

KW - Research Support, Non-U.S. Gov't

M3 - SCORING: Journal article

C2 - 8672537

VL - 1312

SP - 145

EP - 150

JO - Biochim Biophys Acta

JF - Biochim Biophys Acta

SN - 0006-3002

IS - 2

ER -