Regulation of cyclic AMP by extracellular ATP in cultured brain capillary endothelial cells.
1 In primary unpassaged rat brain capillary endothelial cell cultures (RBECs), using reverse-transcriptase PCR with primers specific for P2Y receptor subtypes, we detected mRNA for P2Y2, P2Y4 and P2Y6, but not P2Y1 receptors. 2 None of the various nucleotides tested reduced forskolin elevated cyclic AMP levels in RBECs. ATP and ATPgammaS, as well as adenosine, enhanced cyclic AMP accumulation in the presence of forskolin. 3 Comparison of the concentration response curves to ATPgammaS with those for ATP and adenosine, at different incubation times, indicated that the response to purine nucleotides was not wholly dependent on conversion to adenosine. Adenosine deaminase abolished the response to adenosine but only reduced the response to ATP by about 50%. These results suggest the participation of a receptor responsive to nucleotides. 4 Isobutylmethylxanthine and 8-sulphophenyltheophylline prevented the cyclic AMP response, while neither 8-cyclopentyl-1, 3-dipropylxanthine nor SCH58261 were effective antagonists. 2-chloradenosine gave a robust response, but neither 2-chloro-N6-cyclopentyladenosine nor CGS 21680 were agonists. 5 These results show that adenosine and ATP can elevate the cyclic AMP levels of brain endothelial cells by acting on receptors which have a pharmacology apparently distinct from known P2Y and adenosine receptors.
Anwar
Z
Z
Department of Cell Physiology and Pharmacology, University of Leicester, Medical Sciences Building, P.O. Box 138, University Road, Leicester LE1 9HN.
Albert
J L
JL
Gubby
S E
SE
Boyle
J P
JP
Roberts
J A
JA
Webb
T E
TE
Boarder
M R
MR
D000241:Adenosine / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology*; D000067956:Adenylyl Cyclase Inhibitors; D000818:Animals; D001921:Brain / Q000166:cytology*; D002196:Capillaries / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D002478:Cells, Cultured; D002560:Cerebrovascular Circulation / Q000502:physiology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000502:physiology*; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000187:drug effects / Q000378:metabolism; D058472:Receptors, Purinergic P2Y1; D058473:Receptors, Purinergic P2Y2; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000067956:Adenylyl Cyclase Inhibitors; D016861:Cyclooxygenase Inhibitors; C546384:P2ry1 protein, rat; C546387:P2ry2 protein, rat; D010726:Phosphodiesterase Inhibitors; D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; D018048:Receptors, Purinergic P2; D058472:Receptors, Purinergic P2Y1; D058473:Receptors, Purinergic P2Y2; C104749:purinoceptor P2Y4; C099845:purinoceptor P2Y6; D005576:Colforsin; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D000241:Adenosine