RT Journal Article
SR Electronic
T1 Histamine Increases Interstitial Adenosine Concentration via Activation of Ecto-5′-nucleotidase in Rat Hearts in Vivo
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 71
OP 76
VO 298
IS 1
A1 Toshio Obata
A1 Shunichiro Kubota
A1 Yasumitsu Yamanaka
YR 2001
UL http://jpet.aspetjournals.org/content/298/1/71.abstract
AB We examined whether histamine enhances the production of interstitial adenosine via stimulation of ecto-5′-nucleotidase (a key enzyme responsible for adenosine production) using microdialysis techniques in in situ rat hearts. The microdialysis probe was implanted in the left ventricular myocardium of anesthetized rats and perfused in the presence of adenosine 5′-monophosphate (AMP). Histamine (10–500 μM) administered into the perfusate had a tendency to increase the adenosine concentration. In the presence of prazosin (50 μM), an antagonist of α1-adrenoceptors, or of chelerythrine (10 μM), a protein kinase C (PKC) inhibitor, and in reserpinized rats, histamine failed to increase the AMP-primed dialysate adenosine concentration. Accumulation of norepinephrine in the extracellular fluid elicited by pargyline (100 μM), a monoamine oxidase inhibitor, significantly increased histamine-induced adenosine production. Okadaic acid (50 μM), an inhibitor of protein phosphatase, enhanced the histamine-induced increase in adenosine concentration. Norepinephrine is known to activate α1-adrenoceptors and PKC. Taken together, the results demonstrate that histamine-released norepinephrine activates both α1-adrenoceptors and PKC, which increased ecto-5′-nucleotidase activity and augmented release of adenosine in rat hearts. The American Society for Pharmacology and Experimental Therapeutics