title: Age-related changes in adenosine in rat coronary resistance vessels.
abstract: 1. The vasodilator effects of adenosine receptor agonists, isoprenaline and histamine were examined in perfused heart preparations from young (4-6 weeks) and mature (12-20 weeks) rats. 2. Adenosine induced a biphasic concentration-dependent decrease in KCl (35 mM) raised coronary perfusion pressure in hearts from young and mature rats, suggesting the presence of both high- and low-affinity sites for adenosine receptors in the two age groups tested. In heart preparations from mature rats, vasodilator responses to adenosine were significantly reduced compared with responses observed in young rats. 3. Responses to 5'-N-ethylcarboxamidoadenosine (NECA) and 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamidoadenosine hydrochloride (CGS-21680) were reduced in preparations from mature rats, whereas the vasodilator actions of N6-cyclopentyladenosine (CPA) and N6-2-(4-aminophenyl)ethyladenosine (APNEA) did not change with age. 4. The results presented in this study suggest that several adenosine receptor subtypes mediate vasodilator responses in the coronary circulation of the rat and that a reduction in response to adenosine with age may be due to changes in the high-affinity receptor site.
authors.affiliation: Rotary Centre for Cardiovascular Research, School of Health Sciences, Griffith University, Southport, Queensland, Australia.
authors.forename: R B
authors.initials: RB
authors.lastname: Rose'Meyer
authors.forename: F A
authors.initials: FA
authors.lastname: Harden
authors.forename: J I
authors.initials: JI
authors.lastname: Varela
authors.forename: G J
authors.initials: GJ
authors.lastname: Harrison
authors.forename: R J
authors.initials: RJ
authors.lastname: Willis
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology*; D019830:Adenosine-5'-(N-ethylcarboxamide) / Q000494:pharmacology; D000367:Age Factors; D000818:Animals; D003331:Coronary Vessels / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D006632:Histamine / Q000494:pharmacology; D008297:Male; D010627:Phenethylamines / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018047:Receptors, Purinergic P1 / Q000032:analysis / Q000502:physiology
chemical_list: D010627:Phenethylamines; D018047:Receptors, Purinergic P1; C061282:2-(4-(2-carboxyethyl)phenethylamino)-5'-N-ethylcarboxamidoadenosine; D019830:Adenosine-5'-(N-ethylcarboxamide); D011189:Potassium Chloride; D006632:Histamine; D000241:Adenosine