ABSTRACT
AIM To investigate the effects of serine/threonine protein phosphatases in regulation of cell signal transduction on voltage-gated potassium and calcium channels in cultured rat trigeminal ganglion (TRG) neurons. METHODS Whole-cell patch clamp technique was used to record the potassium and calcium currents from adult rat TRG neurons before and after perfusion of okadaic acid, a potent inhibitor of the serine/threonine protein phosphatases 1 and 2A. RESULTS Okadaic acid 1 μmol·L-1 inhibited transient outwards potassium currents (IA) by 28.6%, increased delay rectified potassium currents (IK) and calcium currents (ICa) by 22.7% and 20.0%, respectively. okadaic acid 1 μmol·L-1 produced significant hyperpolarizing shifts in the conductance-voltage (G-V) curves and inactivation curves of IA , also produced significant hyperpolarizing shifts in the G-V curves of IK, while it had no effect on the activation and inactivation kinetics of ICa. CONCLUSION Serine/threonine protein phosphatases 1 and 2A may be involved in the modulation of voltage-gated potassium and calcium channels on rat TRG neurons. In addition, voltage-gated potassium and calcium channels show different dependence on the dephosphorylation reactions of PP1 and PP2A phosphatases.
ABSTRACT
This experiment aimed to investigate the effect of adrenergic system in the subnucleus commissuriu of nucleus solitrius tractus (CNTS) on renal nerve discharges. Norepinephrine (NE) was microinjected into the CNTS of rabbits and mean arterial blood pressure (MAP) and renal nerve discharges (FRND) were synchronously recorded. The results indicated that (1) microinjection of norepinephine into the CNTS of rabbit could significantly attenuate the frequency of renal nerve discharge, and at the same time decrease markedly the mean arterial pressure. (2) Microinjection of 0.3 nmol yohimbin into CNTS had no significant influence on FRND and MAP, but could attenuate and even reverse the effects of NE on FRND and MAP. These results suggest that microinjection of NE into CNTS may activate the alpha-adrenorecptor located in CNTS and secondarily produce a depressor effect by attenuating the activity of periphenal sympathetic nervous system.
Subject(s)
Blood Pressure/drug effects , Depression, Chemical , Kidney/innervation , Microinjections , Norepinephrine/pharmacology , Solitary Nucleus/physiology , Sympathetic Nervous System/drug effects , Sympathetic Nervous System/physiopathology , Vasomotor System/physiopathologyABSTRACT
L-homocysteic acid (HCA) and other amino acids were conjugated to rat brain material ( extracted rat brain protein) with glutaraldehyde to form HCA- and amino acids-brain material con-jugates. The specificity of monoclonal antibody (McAb) was tested on serial dilution test and ab-sorption test on enzyme- linked immunosorbent assay (ELISA) using these conjugates as antigens instead of amino acids-BSA (bovine serum albumin) conjugates used previously. The characterized McAb was applied for immunohistochemical staining using PAP (peroxidase antiperoxidase) tech-nique in combination with silver enhancement of diamino-benzene (DAB) products. The results in-dicated that McAb to L-HCA reacted with L-HCA-brain material conjugates, but not with other a-mino acids-brain material conjugates so far tested. McAb absorbed with L-HCA-brain material a-bolished or decreased immunoreactivity of L-HCA-brain material with McAb. The antibody selec-tively stained subpopulation of cells and processes in the hippocampus fixed with glutaradehyde. Absorption of McAb with L-HCA-brain material abolished immunohistochemical staining. These results suggested that McAb was specific for L-HCA-brain materials and could be used for imuno-histocytochemistry. This would provide a new tool for immunohistochemical visualization and locali-zation of L-HCA in the nervous system.
ABSTRACT
Summary: This experiment aimed to investigate the effect of adrenergic system in the subnucleus commissuriu of nucleus solitrius tractus (CNTS) on renal nerve discharges. Norepinephrine (NE) was microinjected into the CNTS of rabbits and mean arterial blood pressure (MAP) and renal nerve discharges (FRND) were synchronously recorded. The results indicated that (1) microinjection of norepinephine into the CNTS of rabbit could significantly attenuate the frequency of renal nerve discharge, and at the same time decrease markedly the mean arterial pressure. (2) Microinjection of 0.3 nmol yohimbin into CNTS had no significant influence on FRND and MAP, but could attenuate and even reverse the effects of NE on FRND and MAP. These results suggest that microinjection of NE into CNTS may activate the alpha-adrenorecptor located in CNTS and secondarily produce a depressor effect by attenuating the activity of peripheral sympathetic nervous system.
ABSTRACT
In the experimental study on the electrophysiology and functions of heart in the animal, the thorax should be opened to expose the heart, at the same time natural breathing is maintained instead of artificial breathing. The key procedure of this new method is to avoid injuring the pleural cavity, so pneumothorax can be prevented. By means of this new method some subject studies have been finished.
Subject(s)
Electrophysiology/instrumentation , Heart/physiology , Models, Animal , Respiration , Swine , Thoracic Surgical Procedures , Time FactorsABSTRACT
In the experimental study on the electrophysiology and functions of heart in the animal, the thorax should be opened to expose the heart, at the same time natural breathing is maintained instead of artificial breathing. The key procedure of this new method is to avoid injuring the pleural cavity, so pneumothorax can be prevented. By means of this new method some subject studies have been finished.
Subject(s)
Animals , Dogs , Rabbits , Electrophysiology , Heart , Physiology , Models, Animal , Respiration , Swine , Thoracic Surgical Procedures , Time FactorsABSTRACT
The Experiments were performed on 63 urethane anesthetized, suxamethonium chloride paralyzed and artificially ventilated rats. The results were as follows: microinjection of L-Arg, NO precursor, into parabrachial nuclei (NPB) resulted in a marked decrease in the mean arterial pressure (MAP), but the heart rate had no significant change. Microinjection of N-nitro-L-arginine (L-NNA), NO synthase inhibitor, into NPB caused a significant increase in MAP. Preinjection of L-NNA and methylene blue into NPB separately blocked the depressor effect elicited by L-Arg. Preinjection of bicuculine, γ-aminobutyric acid (GABA) receptor antagonist, into NPB significantly reduced or abolished the depressor effect elicited by L-Arg. The above results indicated that: (1) NO has depressor effect in NPB by activating guanylate cyclase; (2) Endogenous NO in NPB has tonic depressor effect and takes part in maintenance of normal blood pressure level; (3) The depressor effect evoked by NO in NPB is at least partly mediated by local GABA receptor.
ABSTRACT
Experiments were carried out in 31 urethane anesthetized, Suxamethonium chloride paralyzed and artificially ventilated rats. The results were as follows: microinjection of γ-amino butyric acid (GABA) into parabrachial nuclei (NPB) markedly decreased the mean arterial pressure (MAP) (P＜0. 001), while the microinjection of bicuculine (Bic) into NPB caused a significant increase in MAP (P＜0. 001). The depressor effect of GABA could be blocked by preinjection of Bic in NPB. The above agents microinjected into NPB had no significant effect on heart rate (P＞0. 05). The results indicated that: (1) GABA in NPB exerts tonic depressor effect; (2) Endogenous GABA in NPB exerts tonic depressor action and takes part in maintenance of normal blood pressure level.
ABSTRACT
AIM: To determine the effect of hydrogen peroxide(H_2O_2) on voltage-gated potassium channel currents(IKv) in pulmonary vascular smooth muscle cells(PASMCs).METHODS: Using whole cell patch-clamp technique,IKv was recorded in freshly isolated rat PASMCs with acute enzymatic digestion method.The effect of hydrogen peroxide on IKv in PASMCs was investigated in normoxia.RESULTS: IKv in PASMCs was increased significantly by H_2O_2 and the increase depended on the concentration in normoxia.Current-voltage relationship curve shifted to the left.CONCLUSION: Hydrogen peroxide is an important K~+ channel opener.
ABSTRACT
AIM:To determine the role of Kv1 2, Kv1 5, Kv2 1 in the hypoxia pulmonary vasoconstriction (HPV). METHODS: Male Wistar rats were divided into two groups: normoxic group and hypoxic group. The single smooth muscle cell was obtained from pulmonary artery of Wistar rats with acute enzymatic digestion method. The conventional whole-cell patch clamp technique was used to record the resting membrane potential (Em) and the potassium currents of voltage-gated potassium channel (IKv) in rat pulmonary arterial smooth muscle cells (PASMC). Intracellular application of Kv1 2/Kv1 5/Kv2 1 antibodies (1∶125) was conducted through the whole-cell patch clamp system. RESULTS: ① Em of PASMC was depolarized after 24 h hypoxia compared with that of control cells [from (-51 8?0 8) mV to (-47 2? 0 7) mV, P