PURPOSE: The purpose of this study was to investigate the activation of the respiratory centers during insufflation of the larynx with CO2 at different flow rates and concentrations. MATERIALS AND METHODS: The experiments were carried out in spontaneous air breathing rabbits, anesthetized with thiopental sodium (25mg kg(-1) i.v.). The larynx was separated from the oropharyngeal cavity and the trachea. The tidal volume (VT) and respiratory frequency (f min(-1)) were recorded from the lower tracheal cannula. The respiratory minute volume (VE) was calculated, the action potentials from the right phrenic nerve were recorded and the inspiratory (TI) and expiratory (TE) periods and the mean inspiratory flow rate (VT/TI) were calculated. The larynx was insufflated at flow rates of 500mL min(-1) and 750mL min(-1), with 7 and 12% CO2-Air by means of a respiratory pump. RESULTS: Insufflation of the larynx, with both gas mixtures, decreased the f and VT significantly. The TI and TE were found to increase significantly due to the decreasing in f. There was a significant decrease in VT/TI ratio. Following bilateral midcervical vagotomy, on the passing of both gas mixtures, significant decreases were observed in the VT, and the responses of f, TI and TE were abolished. After cutting the superior laryngeal nerve, the responses of the VT to both gas mixtures were abolished. CONCLUSION: In conclusion, the results of this study purpose that the stimulation of the laryngeal mechanoreceptors by the effect of hyper- capnia decreases the activation of the respiratory center
Air ; Animals ; Carbon Dioxide/chemistry/*pharmacology ; Female ; Laryngeal Nerves/drug effects/physiology ; Male ; Mechanoreceptors/drug effects/physiology ; Rabbits ; Reflex/*drug effects/physiology ; *Respiratory Mechanics/drug effects ; Tidal Volume

AIMTo study the effect of volume expansion by 0.9% and 1.8% sodium solution on cardiac-renal reflex activity and the role of cardiac-renal reflex in the regulation of integrated function.

METHODS18 health pentobarbital-anaesthetized rabbits were divided evenly into 2 groups at random, bilateral sino-aortic denervation, intubated via right jugular vein to monitor CVP, left renal nerve separated and ending sectioned to record ERSNA, bilateral ureter intubated to collect urine, right femoral intubated to get blood sample. 15% of whole body blood volume of 0.9% and 1.8% sodium solution were injected via jugular vein 10 ml per minute respectively. The CVP, ERSNA, bilateral urine volume and coefficient of sodium excretion were measured before treated, during treated, one minute, five minutes and ten minutes after treated.

RESULTSVolume expansion by 0.9% and 1.8% sodium solution respectively resulted in the increase of CVP by 64.00% +/- 15.56% and 77.00% +/- 23.74%; the decrease of the frequency of ERSNA by 44.00% +/- 13.64% and 63.00% +/- 12.49%, the average burst time of ERSNA by 37.00% +/- 16.49% and 31.00% +/- 10.69%, the increase of average interval of ERSNA bursts by 60.00% +/- 18.38% and 68.00% +/- 27.04%; the increase of urine volume by 158.00% +/- 28.10% and 640.00% +/- 155.39% in left kidney, 192.00% +/- 32.26% and 1343.00% +/- 429.95% in the right; the increase of coefficient of sodium excretion by 132.00% +/- 35.23% and 376.00% +/- 121.72% in the left, 300.00% +/- 76.99% and 856.00% +/- 261.48% in the right.

CONCLUSIONVolume expansion by different solution stimulate the receptors of cardiopulmonary and regulate the water and sodium excretion of the kidney by the cardiac-renal reflex to modulate the stabilization of blood volume.

Animals ; Blood Volume ; drug effects ; physiology ; Central Venous Pressure ; Heart ; drug effects ; innervation ; Kidney ; drug effects ; innervation ; Rabbits ; Reflex ; Saline Solution, Hypertonic ; pharmacology

BACKGROUNDNicotine may improve schizophrenia patient's cognitive deficit symptoms. This study was to explore the chronic effects of smoking on prepulse inhibition of the startle reflex (PPI) and P50 in the patients with first-episode schizophrenia (FES).

METHODSThe event-related potentials (ERP) recording and analysis instrument made by Brain Products, Germany, was used to detect PPI and P50 in 49 male FES patients (FES group, n = 21 for smokers and n = 28 for non-smokers) and 43 normal male controls (control group, n = 19 for smokers and n = 24 for non-smokers).

RESULTSCompared with normal controls, the FES group had prolonged PPI latency when elicited by single stronger stimulus (P < 0.05); the FES group had prolonged PPI latency and increased PPI amplitude (P < 0.05, 0.01) when elicited by weak and strong stimuli. The FES group had lower PPI inhibition rate than normal controls (P < 0.05). Compared with normal controls, the FES group had increased P50-S2 amplitude and increased amplitude ratio S2/S1 (both P <0.05). In the control group, the smokers had a tendency of increase in P50-S2 amplitude (P > 0.05) and shorter P50-S2 latency (P < 0.05) than the non-smokers. The smokers had higher PPI amplitude than the non-smokers (P < 0.05). In the FES group, the smokers had higher P50-S1 amplitude, shorter P50-S2 latency, and higher amplitude ratio S2/S1 than the non-smokers (P < 0.05, 0.01). The smokers had higher PPI amplitude than the non-smokers (P < 0.05).

CONCLUSIONSThere is obvious PPI and P50 deficits in schizophrenic patients. However, these deficits are relatively preserved in the smokers compared with the non-smokers, which suggests that long-term smoking might partially improve the sensory gating in schizophrenic patients. Whether this conclusion can be deduced to female patients requires further follow-ups.

Adult ; Case-Control Studies ; Evoked Potentials ; drug effects ; physiology ; Humans ; Male ; Reflex, Startle ; physiology ; Schizophrenia ; physiopathology ; Smoking ; adverse effects ; Young Adult

The purpose of this study was to determine the effect of nitric oxide (NO) in the rostral ventrolateral medulla (RVLM) on the central integration of the cardiac sympathetic afferent reflex (CSAR) in normal rats and in rats with coronary ligation-induced chronic heart failure (CHF). Under alpha-chloralose and urethane anesthesia, mean arterial pressure, heart rate and renal sympathetic nerve activity (RSNA) were recorded at baseline and during elicitation of the CSAR evoked by electrical stimulation of the cardiac afferent sympathetic nerves in sino-aortic denervated and cervical vagotomized rats. A cannula was inserted into the left RVLM for microinjection of NO synthase inhibitor, S-methyl-L-thiocitruline (MeTC) or NO donor, S-nitroso-N-acetyl-penicillamine (SNAP). The CSAR was tested by electrical stimulation (5, 10, 20 and 30 Hz at 10 V for 1 ms) of the afferent cardiac sympathetic nerves. It was observed that (1) the responses of RSNA to stimulation were enhanced in rats with CHF; (2) MeTC (80 nmol) potentiated the responses of RSNA to stimulation in sham rats but not in rats with CHF; (3) SNAP (50 nmol) depressed the enhanced RSNA response to stimulation in CHF rats but had no effect in sham rats; and (4) MeTC increased the baseline RSNA and MAP only in sham rats, but SNAP inhibited the baseline RSNA and MAP in both sham and CHF rats. These results indicate that reductance of NO in the RVLM is involved in the augmentation of CSAR in CHF rats.
Afferent Pathways ; physiopathology ; Animals ; Heart Failure ; physiopathology ; Male ; Medulla Oblongata ; physiopathology ; Nitric Oxide ; metabolism ; physiology ; Rats ; Rats, Sprague-Dawley ; Reflex ; physiology ; Sympathetic Nervous System ; drug effects ; physiopathology

BACKGROUNDThe neurogenic bladder dysfunction caused by spinal cord injury is difficult to treat clinically. The aim of this research was to establish an artificial bladder reflex arc in rats through abdominal reflex pathway above the level of spinal cord injury, reinnervate the neurogenic bladder and restore bladder micturition.

METHODSThe outcome was achieved by intradural microanastomosis of the right T13 ventral root to S2 ventral root with autogenous nerve grafting, leaving the right T13 dorsal root intact. Long-term function of the reflex arc was assessed from nerve electrophysiological data and intravesical pressure tests during 8 months postoperation. Horseradish peroxidase (HRP) tracing was performed to observe the effectiveness of the artificial reflex.

RESULTSSingle stimulus (3 mA, 0.3 ms pulses, 20 Hz, 5-second duration) on the right T13 dorsal root resulted in evoked action potentials, raised intravesical pressures and bladder smooth muscle, compound action potential recorded from the right vesical plexus before and after the spinal cord transaction injury between L5 and S4 segmental in 12 Sprague-Dawley rats. There were HRP labelled cells in T13 ventral horn on the experimental side and in the intermediolateral nucleus on both sides of the L6-S4 segments after HRP injection. There was no HRP labelled cell in T13 ventral horn on the control side.

CONCLUSIONUsing the surviving somatic reflex above the level of spinal cord injury to reconstruct the bladder autonomous reflex arc by intradural microanastomosis of ventral root with a segment of autologous nerve grafting is practical in rats and may have clinical applications for humans.

Anastomosis, Surgical ; Animals ; Atropine ; pharmacology ; Male ; Models, Theoretical ; Rats ; Rats, Sprague-Dawley ; Reflex, Abdominal ; drug effects ; physiology ; Trimethaphan ; pharmacology ; Urinary Bladder, Neurogenic ; physiopathology