Stimulation of ANP secretion by 2-Cl-IB-MECA through A(3) receptor and CaMKII.
Adenosine is a potent mediator of myocardial protection against hypertrophy via A(1) or A(3) receptors that may be partly related to atrial natriuretic peptide (ANP) release. However, little is known about the possible involvement of the A(3) receptor on ANP release. We studied the effects of the A(3) receptor on atrial functions and its modification in hypertrophied atria. A selective A(3) receptor agonist, 2-chloro-N(6)-(3-iodobenzyl) adenosine-5'-N-methyluronamide (2-CI-IB-MECA), was perfused into isolated, beating rat atria with and without receptor modifiers. 2-CI-IB-MECA dose-dependently increased the ANP secretion, which was blocked by the A(3) receptor antagonist, but the increased atrial contractility and decreased cAMP levels induced by 30muM 2-CI-IB-MECA were not affected. The 100muM 2-(1-hexylnyl)-N-methyladenosine (HEMADO) and N(6)-(3-iodobenzyl) adenosine-5'-N-methyluronamide (IB-MECA), A(3) receptor agonist, also stimulated the ANP secretion without positive inotropy. The potency for the stimulation of ANP secretion was 2-CI-IB-MECA>>IB-MECA=HEMADO. The inhibition of the ryanodine receptor or calcium/calmodulin-dependent kinase II (CaMKII) attenuated 2-CI-IB-MECA-induced ANP release, positive inotropy, and translocation of extracellular fluid. However, the inhibition of L-type Ca(2+) channels, sarcoplasmic reticulum Ca(2+)-reuptake, phospholipase C or inositol 1,4,5-triphosphate receptors did not affect these parameters. 2-CI-IB-MECA decreased cAMP level, which was blocked only with an inhibitor of CaMKII or adenylyl cyclase. These results suggest that 2-CI-IB-MECA increases the ANP secretion mainly via A(3) receptor activation and positive inotropy by intracellular Ca(2+) regulation via the ryanodine receptor and CaMKII.
Yuan
Kuichang
K
Department of Physiology, Diabtes Research Center, Chonbuk National University Medical School, 2-20 Keum-Am-Dong-San, Jeonju 561-180, Republic of Korea.
Bai
Guang Yi
GY
Park
Woo Hyun
WH
Kim
Sung Zoo
SZ
Kim
Suhn Hee
SH
D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D058909:Adenosine A3 Receptor Agonists; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000502:physiology; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D045604:Extracellular Fluid / Q000378:metabolism; D006325:Heart Atria / Q000378:metabolism / Q000503:physiopathology; D066298:In Vitro Techniques; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism; D008297:Male; D009200:Myocardial Contraction; D051381:Rats; D017207:Rats, Sprague-Dawley; D043684:Receptor, Adenosine A3 / Q000378:metabolism*; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism
C518542:2-hexyn-1-yl-N(6)-methyladenosine; D058909:Adenosine A3 Receptor Agonists; D020746:Calcium Channels, L-Type; D053496:Inositol 1,4,5-Trisphosphate Receptors; D043684:Receptor, Adenosine A3; D019837:Ryanodine Receptor Calcium Release Channel; C084956:N(6)-(3-iodobenzyl)-5'-N-methylcarboxamidoadenosine; D009320:Atrial Natriuretic Factor; D000242:Cyclic AMP; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D010738:Type C Phospholipases; D000241:Adenosine; D002118:Calcium; C090034:2-chloro-N(6)-(3-iodobenzyl)adenosine-5'-N-methyluronamide