[Effect of intracerebroventricular injection of adrenomedullin on catecholaminergic neurons and expression of c-fos in the rat brain nuclei involved in cardiovascular regulation].

Aim And Methods: Using double immunohistochemical method for Fos and tyrosine hydroxylase(TH) to examine the effects of intracerebroventricular (icv) administration of adrenomedullin (AM) on catecholaminergic neurons and the expression of c-fos gene in rat brain nuclei involved in cardiovascular regulation in order to define whether the effects of central administration of adrenomedullin (AM) were induced by activating the catecholaminergic neurons.

Results: (1) Following icy administration of AM (3 nmol/kg), Fos-like immunoreactivity neurons were markedly increased in several brain areas of the rat, including the brainstem, the hypothalamus and the forebrain. (2) Following icy administration of AM (3 nmol/kg), double-labeled neurons for Fos and TH increased significantly in the area postrema (AP), the nucleus of the solitary tract (NTS), the nucleus paragigantocellularis lateralis (PGL) and the locus coeruleus (LC).

[Effect of NO on automaticity of rabbit sino-atrial node].

Aim: To investigate the effects of exogenous NO donors sodium nitroprusside (SNP) and 3-morpholinosydnonimine (SIN-1) on automaticity of the rabbit sino-atrial node in vitro and the action mechanism.

Methods: The intracellular microelectrode technique is used to record the action potentials of rabbit sino-atrial node and APA (amplitude of AP), V(max) (maximal rate of depolarization), VDD (velocity of diastolic depolarization), RPF (rate of pacemaker firing) are analyzed.

Results: SNP(10(-5) - 10(-2) mol/L) increased its RPF and VDD dose-dependently.