[Extracellular adenosine-5'-triphosphate increases intracellular calcium concentration of the rabbit eye suprachoroid via activation of the intracellular signal transduction].
Intracellular calcium concentration ([Ca2+]i) of the rabbit eye suprachoroid was measured with microfluorophotometry using fura-2. Adenosine-5'-triphosphate (ATP) 1-100 microM, added to a perfusing solution, elicited an increase in [Ca2+]i of the suprachoroid. This action of ATP was inhibited when preparations were perfused with a nominally zero Ca2+ Krebs solution or a high magnesium Krebs solution. The [Ca2+]i-increasing action of ATP was attenuated either by lowering temperature or by a phospholipase C inhibitor, compound 48/80. These results indicate that extracellular Ca2+ is necessary to the ATP action and also suggest that the ATP action may be mediated by the intracellular signal transduction which exerts a Ca(2+)-release from intracellular Ca(2+)-store sites. The potency order of ATP-related purine nucleotides was ATP > or = ATP-gamma-S > adenosine-5'-diphosphate (ADP). Adenosine-5'-monophosphate (AMP) and adenosine were not effective. It is concluded that P2-purinoceptors exist on the surface of the suprachoroid and are involved in mechanisms underlying the ATP-induced increase in [Ca2+]i of the suprachoroid.
Shen
Y L
YL
Department of Autonomic Physiology, Tokyo Medical and Dental University, Japan.
Hirai
K
K
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002829:Choroid / Q000378:metabolism*; D005110:Extracellular Space / Q000378:metabolism*; D008297:Male; D011817:Rabbits; D015398:Signal Transduction
D000255:Adenosine Triphosphate; D002118:Calcium