ABSTRACT
<p><b>AIM</b>To investigate the influence of L-arginine (NO donors, L-Arg) on spontaneous contractions of ileum in mice and study the effects of activation of beta-adrenoceptor on NO-induced inhibition in spontaneous contractions of ileum.</p><p><b>METHODS</b>The method of spontaneous contractions recording was used to investigate the effect of L-NNA, ODQ, Isoprenaline( beta-adrenoceptor agonist) and Propranolol (beta-adrenoceptor antagonist) on NO-induced inhibition in spontaneous contractions of ileum.</p><p><b>RESULTS</b>(1) L-Arg inhibited the spontaneous contractions of ileum and had concentration-response relationship. (2) L-NNA (3 x 10(-4) mol/L), ODQ (3 x 10(-6) mol/L) relieved the inhibitory effect of L-Arg in ileum . (3) Propronalol (3 x 10(-6) mol/L) decreased significantly the inhibitory effect of L-Arg. (4) Iso (1 x 10(-7) mol/L) increased the inhibitory effect of L-Arg. After Iso (1 x 10(-7) mol/L) and Propronalol (3 x 10(-6) mol/L) being coapplied, the inhibitory effect of L-Arg was not changed.</p><p><b>CONCLUSION</b>NOS catalyzed L-Arg and produced NO. NO exerted its inhibitory effect by the cGMP pathway, the activation of beta-adrenoceptor was partly involved in NO-induced relaxation in ileum.</p>
Subject(s)
Animals , Mice , Arginine , Pharmacology , Ileum , Physiology , Mice, Inbred Strains , Muscle Contraction , Physiology , Nitric Oxide , Receptors, Adrenergic, beta , MetabolismABSTRACT
<p><b>AIM</b>To explore the modulation of 5-HT on GABA-activated current (I(GABA)) in the membrane of rat dorsal root ganglion (DRG) neurons and its mechanism.</p><p><b>METHODS</b>Rat DRG neurons were isolated mechanically and enzymatically, on which whole-cell patch clamp recording and repatch technique for intracellular dialysis were performed.</p><p><b>RESULTS</b>In the majority of neurons examined (92.0%, 69/75) GABA induced a concentration-dependent inward current. In neurons sensitive to GABA preapplication of 5-HT produced potentiation effect (82.6% , 57/69) on I(GABA). Preapplication of 5-HT at concentrations of 1 x 10(-6), 1 x 10(-5), 1 x 10(-4) and 1 x 10(-3) mol x L(-1) potentiated I(GABA) by (35 +/- 8)% (n=8), (47 +/- 11)% (n=10), (65 +/- 17)% (n=9) and (75 +/- 18)% (n=11), respectively. This effect was mimicked by alpha-methyl-5-HT (1 x 10(-6) mol x L(-1)), a specific 5-HT2 receptor agonist, and reversed by cyproheptadine, a selective 5-HT2 receptor antagonist. The potentiation of I(GABA) by 5-HT was irrespective to whether the I(5-HT) presents or not in a subset of neurons. The concentration-response curves for GABA before and after pretreatment with 5-HT manifested the same threshold value and similar EC50 (2.0 x 10(-5) and 1.9 x 10(-5) mol x L(-1), respectively) , while the maximal value of I(GABA) for the latter was 33.6% higher than that for the former. Intracellular dialysis with GDP-beta-S or H-7 abolished the potentiation of I(GABA) by 5-HT, while H-9 did not.</p><p><b>CONCLUSION</b>5-HT can potentiate GABA-activated current via PKC-dependent phosphorylation of GABA(A) receptor following the activation of 5-HT2 receptor.</p>
Subject(s)
Animals , Female , Male , Rats , 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine , Pharmacology , Cyproheptadine , Pharmacology , Ganglia, Spinal , Cell Biology , Physiology , Membrane Potentials , Neurons , Physiology , Patch-Clamp Techniques , Protein Kinase C , Rats, Sprague-Dawley , Receptors, Serotonin, 5-HT2 , Serotonin , Pharmacology , Serotonin 5-HT2 Receptor Agonists , Serotonin 5-HT2 Receptor Antagonists , Signal Transduction , gamma-Aminobutyric Acid , PharmacologyABSTRACT
<p><b>AIM</b>To examine the effect of sildenafil citrate on penile erection of male rhesus macaque.</p><p><b>METHODS</b>Twenty Macaca mulatta were divided into the sildenafil treated and the control groups of 10 animals each. The penile size, the corpus cavernosal electromyogram (EMG) and the intra-corpus cavernosal pressure (ICP) were determined.</p><p><b>RESULTS</b>The diameter of penis and the ICP were significantly increased and the corpus cavernosal EMG significantly reduced in the sildenafil group.</p><p><b>CONCLUSION</b>Sildenafil citrate increases the penile size and ICP and reduces the corpus cavernosal EMG in male rhesus macaque.</p>