Effect of intracerebroventricular injection of adrenomedullin on catecholaminergic neurons and expression of c-fos in the rat brain nuclei involved in cardiovascular regulation / 中国应用生理学杂志

<p><b>AIM AND METHODS</b>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.</p><p><b>RESULTS</b>(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). (3) Pretreatment with calcitonin gene-related peptide receptor antagonism CGRP (8-37) (30 nmol/kg) significantly reduced the action of AM (3 nmol/kg) in the brain.</p><p><b>CONCLUSION</b>AM activates the nuclei involved in cardiovascular regulation in the forebrain, the hypothalamus and the brainstem, and that the central actions of AM are induced by activating the catecholaminergic neurons of brainstem nuclei involved in cardiovascular regulation. CGRP receptor can mediate the effects of AM in brain.</p>

Effect of NO on automaticity of rabbit sino-atrial node / 中国应用生理学杂志

<p><b>AIM</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>SNP(10(-5) - 10(-2) mol/L) increased its RPF and VDD dose-dependently. 10(-3) mol/L SNP increased RPF (beats/min) from 163 +/- 10.8 to 195.0 +/- 13.1 increased VDD (mV/s) from 50.3 +/- 9.6 to 70.2 +/- 12.1 (P < 0.01). SIN-1(10(-3) - 10(-2) mol/L) also increased RPF and VDD (P < 0.01).10(-4) mo/L Methylene blue (MB), a blocker of GMP cyclase, prevented the positive chronotropic effect and increasement of VDD induced by 10(-3) mol/L SNP totally (P < 0.01). 2. CsCl (2 mmol/L), a blocker of I(f) prevented the increasement of RPF and VDD in part (P < 0.05). 3. NIF (0.46 micromol/L), a blocker of I(Ca-L, had no significant effects on chronotropic effect and increasement of VDD (P < 0.01).</p><p><b>CONCLUSION</b>Exogenous NO can increase the automaticity of rabbit sino-atrial node in vitro. The chronotropic effect is involved in NO-cGMP pathway and results from increasement of I(f) in the sino-atrial node at least in part; I(ca-L) is unlikely to play a major role in this effect.</p>