NG-nitro-L-arginine methyl ester-induced potentiaton of the effect of aminophylline on rat diaphragm: the role of extracellular calcium.
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.
Stojanovic
Radan
R
Department of Clinical Pharmacology, Pharmacology and Toxicology, School of Medicine University of Belgrade, Belgrade, Serbia and Montenegro.
Todorović
Zoran
Z
Nesić
Zorica
Z
Vućković
Sonja
S
Cerovac-Cosić
Natasa
N
Prostran
Milica
M
D000628:Aminophylline / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000502:physiology*; D020746:Calcium Channels, L-Type / Q000502:physiology; D003964:Diaphragm; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D009569:Nitric Oxide / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar
D020746:Calcium Channels, L-Type; D000628:Aminophylline; D009569:Nitric Oxide; D002118:Calcium; D019331:NG-Nitroarginine Methyl Ester