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Objective: This study was designed to observe the antioxidant effects of hyperbaric oxygen (HBO) on brains of rats after acute carbon monoxide (CO) poisoning., Methods: Sixty-six Sprague-Dawley (SD) male rats were divided into three groups including control group, CO group and HBO group.Morris water maze experiments were used for monitoring cognitive function.Antioxidant capacities were evaluated by detecting T-AOC, GSH-PX, GR and CAT activities in the brain., Results: Compared with the control group (45±17, 43±14, 35±12, 34±11, 29±13) s and the HBO group (40±10, 39±6, 35±9, 31±11, 21±10) s, the CO group (57±5, 54±8, 52±8, 52±10, 46±8) s had the longer escape latency (P<0.05). Compared with the control group (51±6) s and the HBO group(40±10) s, the CO group (8±5) s had the shorter swimming time in I quadrant (P<0.05). Compared with the control group (1.25±0.40) U/mg and the HBO group(0.97±0.31, 0.97±0.39, 1.45±0.15, 1.40±0.25, 1.20±0.20) U/mg, the CO group (0.68±0.09, 0.45±0.17, 0.71±0.18, 0.69±0.29, 0.48±0.29) U/mg had the lower T-AOC activity of brain tissue.The GSH-PX activity (42±13, 106±46, 197±49, 173±42, 429±58) U/mg in the CO group decreased compared with the control group (182±53) U/mg and the HBO group (203±63, 325±86, 389±29, 385±100, 453±32) U/mg.GR activity (4.3±0.7, 2.6±0.5, 3.0±1.2, 1.8±0.8, 3.2±1.9) U/mg in the CO group decreased compared with the control group(14.5±3.0) U/mg and the HBO group (13.9±3.3, 4.3±1.0, 3.9±0.7, 4.8±0.9, 4.6±0.9) U/mg.CAT activity (1.6±0.8, 4.3±1.6, 3.9±1.0, 8.5±2.6, 5.4±1.7) U/mg in the CO group decreased compared with the control group(5.2±1.3) U/mg and the HBO group (5.2±2.2, 8.8±2.8, 5.3±1.0, 9.2±2.1, 14.1±3.8) U/mg., Conclusions: HBO can improve the behavior of rats after acute CO poisoning.The antioxidant capacity in rat brain tissue after acute CO poisoning decreases, while after the HBO therapy, the antioxidant capacity in rat brain tissue can increase.

The aim of the present study was to investigate the effect of a short-term (3-day) simulated microgravity with and without daily dorsoventral gravitation (-G(x)) for 1 h on myogenic tone and vasoconstrictor responsiveness of the middle cerebral artery and mesenteric third-order small artery in rats. The tail-suspension (SUS) model was used to simulate cardiovascular deconditioning due to microgravity. Daily restoring to normal standing (STD) posture for 1 h was adopted to provide -G(x) as the countermeasure. Segments of middle cerebral artery and mesenteric third-order small artery were isolated and cannulated. Vascular diameters in response to increased intraluminal pressure (from 20 mmHg to 120 mmHg, by 20 mmHg steps) of isolated arteries under no-flow conditions were recorded by a Pressure Myograph System in both physiologic salt solution (PSS) (active diameter, Da) and calcium-free PSS (passive diameter, Dp). The myogenic tone was calculated by (Dp-Da)/Dpx100%. Vasoconstrictor responsiveness of the isolated middle cerebral artery to serotonin and that of small mesenteric artery to phenylephrine were assessed in the PSS under an intraluminal pressure of 40 mmHg. The results showed that SUS induced an enhancement of the myogenic tone and vasoconstrictor responsiveness in the isolated middle cerebral artery but a depression of those in the small mesenteric artery. Daily STD for 1 h prevented the depression of myogenic tone and vasoconstrictor responsiveness in the small mesenteric artery, but did not prevent the functional enhancement in the middle cerebral artery. These data suggest that a short-term simulated microgravity may result in different alterations in the function of the cerebral artery and the resistance vessel in the hind-body. Moreover, only the decrease of function in these resistance vessels, not in the cerebral arteries, can be prevented by such a countermeasure of daily STD for 1 h.

Aim: To develop a real-time PCR method for quantifying low abundance mRNA expression in rat arterial tissues and examine differential changes of angiotensinogen (AGT) gene expression in basilar and femoral arterial tissues after 8 weeks simulated weightlessness., Methods: After 8-wk of simulation, basilar and femoral arteries were harvested from both simulated weightless (SUS) and control (CON) rats. Then total RNA was extracted and reverse transcribed. The real-time PCR using TaqMan-MGB probe was performed to quantify AGT mRNA expression. The amplification efficiency (E) of PCR was calculated from the slope of standard curve. The threshold cycle (Ct) was detected by changes in fluorescence during a real-time PCR. Finally, the relative expression ratio of the target gene (AGT) to the reference gene (GAPDH) was calculated using E and Ct according to the mathematical model derived from the equation calculating the starting fluorescence (Ro)., Results: After a 8-weeks simulated weightlessness, the AGT mRNA expression increased by 240 percent in basilar arterial, and decreased by 66 percent in femoral arterial tissues., Conclusion: The specificity, sensitivity, precision, reproducibility, and simplicity of real-time PCR method using TaqMan-MGB probe make it particularly suitable for quantification of low abundance mRNA in arterial tissue from rats.

Objective. To investigate whether the changes in rat after simulated weightlessness are similar to those in astronaut after flight. Methods. The effects of 4 wk tail-suspension on left ventricular structure and function in rats were examined by echocardiography. Results. After 4 wk of simulated weightlessness, the thickness of both the anterior and posterior wall in left ventricle (LV) showed a general trend of decrease, but these changes were not statistically significant; the end-systolic and end-diastolic internal dimensions (ESD and EDD respectively) of LV decreased significantly; and the end-systolic volume, end-diastolic volume and stroke volume (ESV, EDV and SV respectively) were all reduced; so did the relevant indices of them. There were no significant differences in ejection fraction (EF) and fractional shortening (FS) between the tail-suspended and control groups. The left ventricular mass (LVM) and its index (LVMI) were decreased. The peak velocities of blood flow of aorta, pulmonary artery and mitral valve didn't show any significant change after simulated weightlessness. Conclusion. Medium-term simulated weightlessness may lead to a significant decrease in left ventricular internal dimension, ventricular volume, and mass, and a trend of decrease in mean left ventricular wall thickness. These changes in rats are similar to those observed in astronauts postflight.

The effects of ephedrine (Eph) were compared with those of tyramine (Tyr) and phenylephrine (Phe) in ring segments of guinea pig portal vein in vitro. Eph (3-1000 mumol/L), Tyr (10-1000 mumol/L) and Phe (1-1000 mumol/L) all produced concentration-dependent contractile responses, which were exceedingly depressed by alpha-adrenoceptor blocker phentolamine (31 mumol/L). Pretreatment with reserpine 1 mg/(kg.d) x 2 d markedly diminished the effect of Tyr, but greatly potentiated the effects of Eph and Phe. Both Eph (1-30 mumol/L) and Tyr (10-100 mumol/L), but not Phe, significantly increased the electrical field stimulation (duration 2 ms, 3 Hz, 10 s, 50 V, 10 min intervals) evoked contractions of the portal veins. beta-Adrenoceptor blocker propranolol (0.5 mumol/L) greatly inhibited this effect of Eph, without affecting that of Tyr. It is suggested that the effect of Tyr is mainly due to its release of endogenous norepinephrine (NE) from the nerve terminals; conversely, Eph mainly bcts on postsynaptic alpha-adrenoceptors directly with some NE-releasing action which may involve the activation of presynaptic beta-adrenoceptors.

Antidromic field potentials and antidromic unit responses of Purkinje cells (PCs) to the stimulation of fastigial nucleus (FN), interposed nucleus (IN) and dentate nucleus (DN) were respectively recorded from the lobule VII of posterior cortex of decerebrated cats, to identify the corticonuclear projection in the lobule VII. After antidromically identified, simple and complex spike responses of PCs to natural peripheral forepaw extension-flexion stimuli were observed. All data were analysed by a computer, and average field potentials and poststimulus time histograms (PSTHs) were constructed. The results show that the corticonuclear zones are sharply demarcated on the lobule VII of posterior cortex. The boundary between the fastigial zone (FZ) and the interposed zone (IZ) on the lobule VII is not straight, but bends. Among sublobule VII Aa-VII Ad the FZ-IZ boundary bends from 2.8 mm to 1.5 mm laterally to the midline. The boundary between IZ and dentata zone (DZ) was about 5.0 mm away from the midline. The PSTHs of the simple and complex spike activities showed that part of PCs in all three different corticonuclear zones responded to the forepaw flexion-extension stimulation, but proportion of the cells affected was quite different among the three zones. In the IZ 84% PCs were modulated by the forepaw stimulation, while in the FZ and DZ it was 59% and 20% respectively. These results support previous finding that information processing involved in the modulation of Purkinje cell activity in response to the forepaw stimulation occurs in all 3 zones examined.