A1 and A2 adenosine receptor activation inversely modulates potassium currents and membrane potential in DDT1 MF-2 smooth muscle cells.
Adenosine receptors are widely distributed in mammalian tissues and have been possibly involved through transmembrane potential changes in cell function regulation. The effect of A1 and A2A adenosine receptor ligands on transmembrane potential measured with flow cytometry and potassium conductance measured by the patch-clamp technique was investigated in DDT1 MF-2 smooth muscle cells. The A1 adenosine-receptor agonist CPA (50 nM) and the A2A adenosine-receptor agonist CGS 21680 (50 nM) elicited a rapid and maintained increase and decrease in the potassium conductance, respectively, and a concomitant hyperpolarization and depolarization of the membrane, respectively. These effects were eliminated by subtype-selective adenosine receptor antagonists (DPCPX, CSC, ZM 241385, all 1 microM). The ligand induced membrane potential changes were reversible. Based on these detected membrane potential changes along with the published voltage dependence of the adenylyl cyclase, the regulation of cAMP production by A1- and A2A-receptor activation is suggested to be mediated through the induced early hyperpolarization and depolarization. The interaction between the effects of these receptor subtypes allows for a complex regulation mechanism.
Márián
Teréz
T
Positron Emission Tomograph Centre, University of Debrecen, Hungary.
Rubovszky
Bálint
B
Szentmiklósi
A József
AJ
Trón
Lajos
L
Balkay
László
L
Boros
István
I
Gáspár
Rezsö
R
Székely
Andrea
A
Krasznai
Zoltán
Z
D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015221:Potassium Channels / Q000378:metabolism*; D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; D018047:Receptors, Purinergic P1 / Q000378:metabolism*
D015221:Potassium Channels; D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; D018047:Receptors, Purinergic P1