Effects of adenosine analogues on tension and cytosolic Ca2+ in porcine coronary artery
| Autor: | H. A. Olanrewaju, S. J. Mustafa |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
Male
medicine.medical_specialty Adenosine Contraction (grammar) Swine Physiology chemistry.chemical_element Buffers In Vitro Techniques Calcium Cytosol Physiology (medical) Muscle tension Internal medicine medicine Extracellular Animals Receptor Fluorescent Dyes Dose-Response Relationship Drug Chemistry Arteries Coronary Vessels Adenosine receptor Endocrinology Purinergic P1 Receptor Antagonists Vasoconstriction Second messenger system Fura-2 Cardiology and Cardiovascular Medicine medicine.drug |
| Zdroj: | American Journal of Physiology-Heart and Circulatory Physiology. 270:H134-H141 |
| ISSN: | 1522-1539 0363-6135 |
| Popis: | This study evaluates the relaxing effects of adenosine analogues in relation to intracellular free Ca2+ concentration ([Ca2+]i) in porcine coronary artery. Changes in muscle tension and [Ca2+]i were measured simultaneously using the fluorescent Ca2+ indicator, fura 2-acetoxymethyl ester. The ratio of fluorescence due to excitation at 340 nm to that at 380 nm reflects [Ca2+]i. Increased tension of the porcine coronary artery contracted with prostaglandin F2 alpha (PGF2 alpha, 20 microM) was accompanied by increased [Ca2+]i. The adenosine analogues, N6-cyclopentyladenosine (CPA), 2-chloroadenosine (CAD), and 2-[m-(carboxyethyl)-phenylamino]-5'-N-ethylcarboxamidoadenosine (CGS-22988) produced a concentration-dependent (10(-8)-10(-4) M) reduction of [Ca2+]i and tension with a maximum relaxation of approximately 96% and a [Ca2+]i decrease of 88% at a concentration of 10(-4) M. The order of potency for relaxation was CAD > CGS-22988 = CPA. Adenosine receptor antagonists (8-phenyltheophylline, 10(-6) M; CGS-15943, 10(-5) M) shifted the agonist-mediated relaxation and [Ca2+]i curve to the right in a parallel fashion. In Ca(2+)-free buffer, PGF2 alpha (20 microM)-induced contraction was significantly reduced (75%). PGF2 alpha also caused a transient increase in [Ca2+]i that later was reduced below the resting level. The order of potency for relaxation for adenosine analogues in Ca(2+)-free buffer was found to be CAD = CGS-22988 > CPA. All curves were shifted to the right in the presence of receptor antagonists. These results indicate that adenosine receptor-mediated changes in [Ca2+]i and relaxation in porcine coronary smooth muscle are at least partly independent of extracellular Ca2+. |
| Databáze: | OpenAIRE |
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