Effects of clonidine on myocardial beta-adrenergic receptor-adenyl cyclase-cAMP system after scalds in rats
Abstract
AIM: To study the role of clonidine (Clo) on the myocardial beta-adrenergic
receptor (beta-AR)-adenyl cyclase (AC)-cAMP system after the scalds in rats.
METHODS: A 30% skin-full-thickness scald was produced by immersing rats in 95
degrees C water for 9 s. Clo 0.1-3.0 mg.kg-1 was injected i.p. to rats at 30 min
before scalds, yohimbine (Yoh) 0.05 mg.kg-1 or prazosin (Pra) 0.03 mg.kg-1 to
rats at 30 min before i.p. Clo. beta-AR density and affinity, AC activity,
phosphoric diester hydrolases (PDH) activity, and cAMP content were determined
with radioreceptor assay, indirect method, enzymeradiochemical assay, and
radioimmunoassay, respectively.
RESULTS: Clo inhibited the decrease of the myocardial beta-AR density, the
attenuation of AC activity, and the reduction of cAMP content at 12 h after the
scalds. Yoh partially reversed the effects of Clo on the three parameters. But
Pra did not.
CONCLUSION: Clo reversed the changes of the myocardial beta-AR-AC-cAMP system
resulted from the scalds in rats.
Keywords:
receptor (beta-AR)-adenyl cyclase (AC)-cAMP system after the scalds in rats.
METHODS: A 30% skin-full-thickness scald was produced by immersing rats in 95
degrees C water for 9 s. Clo 0.1-3.0 mg.kg-1 was injected i.p. to rats at 30 min
before scalds, yohimbine (Yoh) 0.05 mg.kg-1 or prazosin (Pra) 0.03 mg.kg-1 to
rats at 30 min before i.p. Clo. beta-AR density and affinity, AC activity,
phosphoric diester hydrolases (PDH) activity, and cAMP content were determined
with radioreceptor assay, indirect method, enzymeradiochemical assay, and
radioimmunoassay, respectively.
RESULTS: Clo inhibited the decrease of the myocardial beta-AR density, the
attenuation of AC activity, and the reduction of cAMP content at 12 h after the
scalds. Yoh partially reversed the effects of Clo on the three parameters. But
Pra did not.
CONCLUSION: Clo reversed the changes of the myocardial beta-AR-AC-cAMP system
resulted from the scalds in rats.