title: ATP-induced calcium transient in cultured rat aortic smooth muscle cells.
abstract: To characterize the excitatory purinoceptors in vascular smooth muscle cells and the biochemical mechanisms of their actions, the effects of ATP and other nucleotides on Ca2+ mobilization in cultured smooth muscle cells mainly from rat aorta were investigated. ATP induced a transient and dose-dependent increase in the cytosolic Ca2+ concentration. ATP also induced a rapid production of inositol trisphosphate (IP3). The agonist form of ATP was metal-free ATP and its half-maximal effect was obtained at about 0.1 microM. 4-beta-Phorbol 12-myristate 13-acetate (PMA) or 8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate (TMB-8) inhibited both Ca2+ response and IP3 production. In addition, TMB-8 but not PMA, significantly decreased the amount of releasable Ca2+ presumably in the sarcoplasmic reticulum. Pertussis toxin also inhibited the Ca2+ response. Based on the dose-dependent effects of various nucleotides and adenosine on the Ca2+ response, it was concluded that the P2 subclass of purinoceptor is involved in the observed ATP effects. In addition, the observed absence or very weak effect of alpha, beta-methylene ATP relative to the effect of ATP suggests that the excitatory P2-purinoceptors in vascular smooth muscle cells do not form a homogeneous group, because the opposite order of potency for these two nucleotides was reported previously for the P2 purinoceptors involved in contraction of some isolated blood vessels.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D001011:Aorta / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism; D005707:Gallic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000096:biosynthesis; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D037342:Pertussis Toxin; D051381:Rats; D011983:Receptors, Purinergic / Q000187:drug effects / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
chemical_list: D002121:Calcium Channel Blockers; D007295:Inositol Phosphates; D011983:Receptors, Purinergic; D010566:Virulence Factors, Bordetella; C006014:8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate; D005707:Gallic Acid; D015544:Inositol 1,4,5-Trisphosphate; D000255:Adenosine Triphosphate; D037342:Pertussis Toxin; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium