Adenosine A1-receptor stimulation of inositol phospholipid hydrolysis and calcium mobilisation in DDT1 MF-2 cells.
1. The effect of adenosine receptor-stimulation on inositol phospholipid hydrolysis and calcium mobilization has been investigated in the hamster vas deferens smooth muscle cell line DDT1 MF-2. 2. Adenosine receptor stimulation increased the accumulation of total [3H]-inositol phosphates in DDT1 MF-2 cells prelabelled with [3H]-myo-inositol. The rank order of agonist potencies was N6-cyclopentyladenosine greater than 5'-N-ethylcarboxamidoadenosine greater than 2-chloroadenosine greater than adenosine. 3. The response to 2-chloroadenosine was antagonized by the antagonists 8-cyclopentyl-1,3-dipropylxanthine (KD 1.2 nM), PD 115,199 (KD 39 nM) and 8-phenyltheophylline (KD 31 nM). 4. The inositol phosphate response to 2-chloradenosine (10 microM) was not significantly altered when the extracellular Ca2+ ion concentration was reduced from 2.4 mM to 1.2 mM or 0.6 mM. Under calcium-free conditions, however, a reduced but still significant response to 2-chloroadenosine was evident (39 +/- 10% of the response in calcium-containing medium). 5. The 5-lipoxygenase inhibitor AA861 (10 and 100 microM) inhibited the inositol phosphate response to 2-chloroadenosine by 40 +/- 9% and 60 +/- 4% respectively. The cyclo-oxygenase inhibitor, indomethacin, however, was without significant effect at 1 microM. 6. 2-Chloroadenosine stimulated an increase in intracellular free Ca2+ ion concentration in fura-2 loaded DDT1 MF-2 cells in calcium-free medium containing 0.1 mM EGTA, which could be inhibited by the adenosine A1-receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (0.1 microM). 7. These data suggest that adenosine A1-receptor stimulation results in inositol phospholipid hydrolysis and calcium mobilization from intracellular stores in DDT1 MF-2 cells.
White
T E
TE
Department of Physiology & Pharmacology, Medical School, Queen's Medical Centre, Nottingham.
Dickenson
J M
JM
Alexander
S P
SP
Hill
S J
SJ
D015762:2-Chloroadenosine / Q000494:pharmacology; D000241:Adenosine / Q000494:pharmacology; D000818:Animals; D016227:Benzoquinones / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D006224:Cricetinae; D006868:Hydrolysis; D007213:Indomethacin / Q000494:pharmacology; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology; D008297:Male; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism*; D011983:Receptors, Purinergic / Q000378:metabolism*
D016227:Benzoquinones; D016859:Lipoxygenase Inhibitors; D010716:Phosphatidylinositols; D011983:Receptors, Purinergic; D015762:2-Chloroadenosine; C036837:2,3,5-trimethyl-6-(12-hydroxy-5,10-dodecadiynyl)-1,4-benzoquinone; D000241:Adenosine; D002118:Calcium; D007213:Indomethacin