Stojanovic R, Todorović Z, Nesić Z, Vućković S, Cerovac-Cosić N, Prostran M. NG-Nitro-L-arginine Methyl Ester-Induced Potentiaton of the Effect of Aminophylline on Rat Diaphragm: the Role of Extracellular Calcium.
J Pharmacol Sci 2004;
96:493-8. [PMID:
15599090 DOI:
10.1254/jphs.sce04001x]
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Abstract
The role of extracellular calcium in the interaction between intracellular cAMP and nitric oxide (NO)/cGMP on the contractility of rat diaphragm pretreated with cumulative concentrations of aminophylline (0.36 - 3.60 mM) was investigated. In a Ca2+-free medium, NG-nitro-L-arginine methyl ester (L-NAME) (1 and 3 mM) depressed tension developed (Td) and also aminophylline-induced potentiation of Td in a concentration-dependent manner. Verapamil (2.5 microM) or nicardipine (20 microM) significantly antagonized the potentiating effect of L-NAME on Td in a calcium-containing medium. However, in the presence of verapamil or nicardipine, L-NAME still produced statistically significant potentiation of the cumulative concentrations of aminophylline (0.36 - 3.60 mM), given in the second series.
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