PROSTRAN, M. (7004009031)M. (7004009031)PROSTRANVARAGIć, V.M. (7006591279)V.M. (7006591279)VARAGIć2025-07-022025-07-021989https://doi.org/10.1111/j.1472-8206.1989.tb00678.xhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-0024444506&doi=10.1111%2fj.1472-8206.1989.tb00678.x&partnerID=40&md5=042e4aed7a535ec02c3844f93bcc8db3https://remedy.med.bg.ac.rs/handle/123456789/14747Summary— Similar to adenosine and some of its derivatives, 5′‐N‐ethylcarboxamideadenosine (NECA) produced a biphasic effect on the isolated hemidiaphragm of the rat: a potentiation of the isometric contraction during direct electrical stimulation (in the presence of dipyridamole), and a depression during indirect electrical stimulation, and particularly so in a partially curarized preparation. The potentiating effect is presumed to be due to activation of the cAMP system, probably through A2 receptor sites, although a differentiation of the receptor subtype could not be made with aminophylline and XAC. Inhibition is most probably due to a depressant action of NECA on the acetylcholine release from the motor nerve terminals. These results accord with our previous findings, suggesting that adenosine may be part of a buffer system which participates in balancing the excitatory and inhibitory influences on skeletal muscle contraction. 1989 Société Française de Pharmacologie et de Thérapeutiqueaminophyllineisolated hemidiaphragmNECAskeletal muscleXAC