Effects of ATP on cultured smooth muscle cells from rat aorta

• Published in: British journal of pharmacology Vol. 108; no. 3; pp. 638 - 645
• Main Authors: Weid, P.‐Y., Serebryakov, V.N., Orallo, F., Bergmann, C., Snetkov, V.A., Takeda, K.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.03.1993; Nature Publishing
• Subjects: Adenosine Triphosphate - analogs & derivatives; Adenosine Triphosphate - pharmacology; Animals; Aorta, Thoracic - drug effects; ATP; Biological and medical sciences; Blood vessels and receptors; Calcium - metabolism; Calcium Channels - drug effects; Ca‐dependent Cl channel; Ca‐dependent K channel; Cells, Cultured; Electrophysiology; Fundamental and applied biological sciences. Psychology; internal calcium; Male; Membrane Potentials - drug effects; Muscle Contraction - drug effects; Muscle, Smooth, Vascular - drug effects; Phenotype; purinoceptor; Rats; Rats, Inbred WKY; Vascular smooth muscle; Vertebrates: cardiovascular system; Cell culture; Calcium; Pathophysiology; Rat; Rodentia; Smooth muscle; In vitro; Vertebrata; Vasomotricity; Mammalia; Purinergic receptor; Blood vessel; Aorta; Mechanism of action; ATP
• ISSN: 0007-1188; 1476-5381
• DOI: 10.1111/j.1476-5381.1993.tb12854.x

1 Membrane ionic currents provoked by externally applied ATP were studied by patch‐clamp techniques in cultured aortic smooth muscle cells of the rat. 2 Using standard bath and pipette solutions and whole‐cell voltage‐clamp, ATP evoked an inward current when the cell membrane potential was held at −50 mV and an outward current when the potential was held at 30 mV, with a reversal potential near −10 mV. 3 Application of ATPγS gave results similar to those obtained with ATP, while adenosine, AMP and α,β‐methylene ATP were ineffective. The ATP‐activated current was inhibited by suramin, 100 μm. 4 ATP also induced a biphasic rise in internal free Ca levels as shown directly by Fura‐2 measurements and by the increase in Ca‐dependent K single‐channel activity in cell‐attached patches. 5 With outward current through K channels blocked by internal Cs and TEA, modification of the ionic composition of bath and pipette solutions revealed that the reversal potential for the ATP‐induced whole‐cell current closely followed ECl, the chloride equilibrium potential, and was insensitive to manipulations of the monovalent cation gradient. 6 These results indicate that in rat cultured aortic smooth muscle cells, ATP binding to P2‐purinoceptors produces increases of internal free Ca levels and subsequent activation of both Ca‐dependent K and Cl currents.