Effect of 71 ATA He-O2 on organ blood flow in the rat

Aanderud, L; Onarheim, J; Tyssebotn, I

doi:10.1152/jappl.1985.59.5.1369

Cited by 10 publications

(7 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similar matching changes were observed in both groups, although the P a CO 2 increased only in the rats of group 2. The raised SBP cannot be associated with HBO alone, as suggested by Torbati (1987), since a similar rise has been found to occur in normoxic hyperbaric environments (Aanderud et al 1985;Hordnes and Tyssebotn 1985;Stuhr et al 1993;Bergù and Tyssebotn 1995c). On the other hand, f c was only reduced in the hyperoxic atmosphere and may be caused by a direct O 2 eect on the chemoreceptors.…”

Section: Kpa Ambient Pressurementioning

confidence: 58%

“…Previous results have demonstrated that f c and c do not change during normoxic exposures (Aanderud et al 1985;Hordnes and Tyssebotn 1985;Risberg et al 1990;Bergù and Tyssebotn 1995c). However, if P a O 2 is elevated, f c and c are lowered (Bergù et al 1988;Tyssebotn 1992a, 1995a, b;Risberg et al 1995).…”

Section: Kpa Ambient Pressurementioning

confidence: 94%

“…The MS method has been utilized extensively and shown to be reliable both for blood¯ow measurements in normal ambient pressure environments (Rudolph and Heymann 1967;Buckberg et al 1971;Hillerdal et al 1987) and in hyperbaric environments (Aanderud et al 1985;Hordnes and Tyssebotn 1985;Bergù et al 1988;Risberg et al 1990). The method has also been found to be valid for consecutive measurements in small tissue samples (Hillerdal et al 1987;Tyssebotn 1992a, 1995a, b).…”

Section: Validity Of the Ms Methodsmentioning

confidence: 99%

“…The cage had perforated sides to ensure proper ventilation. Rats that were habituated in this manner showed no increase in plasma corticosterone or free fatty acids for the 4 h that they were kept in the con®ned compartment during their HBO exposure (Aanderud et al 1985;Risberg et al 1990). …”

Section: Experimental Animalsmentioning

confidence: 99%

“…Thus, the augmented hemodynamic parameters may be due to the combined eects of the ambient pressure increase per se (Ask and Tyssebotn 1988;Stuhr et al 1989), an increase in breathing gas density (Bergù and Tyssebotn 1992c;Risberg et al 1995), and the O 2 pressure increase (Bergù and Tyssebotn 1995b;Risberg et al 1995). Of these factors, the increase in O 2 pressure has been shown to be most potent since a pressure increase of only 10 kPa O 2 reduces f c and increases cardiac contractility (Risberg et al 1995), whereas normoxic ambient pressures up to 7 MPa (Aanderud et al 1985;Stuhr et al 1989) did not in¯uence the f c , but increased contractility (Ask and Tyssebotn 1988;Stuhr et al 1989). A systemic eect of O 2 radicals does not seem likely, since the eects occur instantly at the start of the O 2 exposures (Bergù and Tyssebotn 1995a, b) and at O 2 pressures as low as 30 kPa (Risberg et al 1995).…”

Section: Kpa Ambient Pressurementioning

confidence: 99%

See 4 more Smart Citations

Cardiovascular effects of hyperbaric oxygen with and without addition of carbon dioxide

Bergø¹,

Tyssebotn²

1999

Eur J Appl Physiol

Self Cite

View full text Add to dashboard Cite

It is commonly believed that during hyperbaric oxygen (HBO) treatment, in spite of the vasoconstriction induced by the increased O2 content in the breathing gas, the elevated carrying capacity of O2 in the arterial blood results in augmented O2 delivery to tissues. The experiments described here tested the hypothesis that HBO treatment would be more efficient in delivering O2 to poorly perfused tissues if the vasoconstriction induced by elevated O2 could be abolished or attenuated by adding CO2 to the breathing gas. Organ blood flow (QOBF), systemic hemodynamics, and arterial blood gases were measured before, during and after exposure to either 300 kPa O2 (group 1) or 300 kPa O2 with 2 kPa CO2 (group 2), in awake, instrumented rats. During the HBO exposure the respiratory frequency (fb) fell (4 breaths x min(-1) x 100 kPa O2(-1)), with no changes in arterial CO2 tension (PaCO2), but when CO2 was added, fb and PaCO2 increased. The left ventricular pressure (LVP) and the systolic arterial pressure (SBP) increased. The maximum velocity of LVP (+dP/dt) rose linearly with LVP whether CO2 was added or not (r2 = 0.72 and 0.75 respectively). Similarly, the cardiac output (Qc) and heart rate (fc) fell, while the stroke volume (SV) was unaltered, independent of PaCO2. There was a general vasoconstriction in most organs in both groups, with the exception of the central nervous system (CNS), eyes, and respiratory muscles. HBO reduced the blood flow to the CNS by 30%, but this vasoconstriction was diminished or eliminated when CO2 was added. In group 2, the blood flow to the CNS rose linearly with increased PaCO2 and decreased pH. After decompression fc and SBP stayed high, while Qc returned to control values by reducing the SV; CNS blood flow remained markedly elevated in group 2, while in group 1, it returned to control levels. We conclude that the changes in fc, Qc, LVP, dP/dt, SBP and most QOBF values induced by HBO were not changed by hypercapnia. Blood flow to the CNS decreased during HBO treatment at a constant PaCO2. Hypercapnia prevented this decline. Elevated PaCO2 augmented O2 delivery to the CNS and eyes, but increased the susceptibility to O2 poisoning. A prolonged suppression of O2 supply to the CNS occurred during the HBO exposure and in air following the decompression in the absence of CO2. This suppression was offset by the addition of CO2 to the breathing gas.

show abstract

Section: Kpa Ambient Pressurementioning

confidence: 58%

Section: Kpa Ambient Pressurementioning

confidence: 94%

Section: Validity Of the Ms Methodsmentioning

confidence: 99%

Section: Experimental Animalsmentioning

confidence: 99%

Section: Kpa Ambient Pressurementioning

confidence: 99%

See 3 more Smart Citations

Cardiovascular effects of hyperbaric oxygen with and without addition of carbon dioxide

Bergø¹,

Tyssebotn²

1999

Eur J Appl Physiol

Self Cite

View full text Add to dashboard Cite

show abstract

Repeated normoxic hyperbaric exposures induce haemodynamic and myocardial changes in rats

Stuhr

Bergø

et al. 1993

Europ. J. Appl. Physiol.

View full text Add to dashboard Cite

The effect of repeated exposure to ambient pressures of 5 bar (500 kPa), in atmospheres comprising normal partial pressures of oxygen [0.2 bar (20 kPa)] and nitrogen [0.8 bar (80 kPa)] and 4 bar (400 kPa) helium, on cardiac function and morphology was assessed in conscious rats. Ten test rats underwent chamber dives daily for 40 consecutive days, and ten control rats were exposed in the same chamber for an equal period of time, but in air at 1 bar (100 kPa). Cardiac output (Qc) and myocardial blood flow (Qmyocardial) were determined by the microsphere method. After 40 days, the body mass was 7% greater in the control than in the test rats (P < 0.05), although they were given exactly the same amount of standard food. The test rats had a significantly higher (7% absolute, 12% ventricular mass to body mass, P < 0.05) heart mass (left ventricular myocardium, including the ventricular septum) than the control rats. The percentage tissue dry mass of the right and left ventricles was equal in the two groups. Microscopic examination revealed a number of small focal necroses in the left ventricle of the test rats but none in the control rats. The left ventricular pressure (LVP) and the maximum velocity of LVP increase (contractility) and decrease were significantly increased (25%-96%, P < 0.001) in the pre-exposed compared to the control rats at 1 bar (100 kPa). The systolic arterial pressure, heart rate and respiratory frequency were similar in the two groups at 1 bar (100 kPa).(ABSTRACT TRUNCATED AT 250 WORDS)

show abstract

Effects of SCH 42495, a neutral endopeptidase inhibitor, on cardiac function and mass in rats after repeated hyperbaric exposures

Stuhr

2000

Scandinavian Journal of Clinical and Laboratory Investigation

View full text Add to dashboard Cite

The aim of the present study was to investigate the effects of inhibition of neutral endopeptidase on left ventricular hypertrophy (LVH), myocardial necrosis and haemodynamic changes, previously shown in rats after repeated hyperbaric exposures to 5 bar, by using the novel neutral endopeptidase inhibitor SCH 42495. Ten test rats underwent chamber dives daily for 40 consecutive days, and 10 control rats were exposed in the same chamber for an equivalent period of time, but in air at 1 bar. The rats received SCH 42495 orally (30 mg/kg twice a day) for 40 days. After 40 days, the body mass was identical in the two groups. Test rats and control rats had equal heart mass (both totally and left ventricular myocardium, including the ventricular septum/100 g), thus indicating that long-term treatment with SCH 42495 inhibits hyperbarically induced LVH. The left ventricular pressure (LVP) and the maximal velocity of LVP increase and decrease (+/- dP/dt) were similar in the test rats compared to the control rats at 1 bar. Previously, we found a higher LVP and dP/dt in non-treated test rats in otherwise identical experiments. This indicates that SCH 42495 "normalizes" the cardiac function of test rats after repeated hyperbaric exposures. The systolic arterial pressure, heart rate (HR) and respiratory frequency (RF) were similar in the two groups throughout the experiments. However, treatment with SCH 42495 lowered the blood pressure compared to previously non-treated rats. In conclusion, long-term administration of the neutral endopeptidase inhibitor SCH 42495 prevented previously shown changes in cardiac function as well as myocardial mass after 40 consecutive exposures to 5 bar.

show abstract

Effect of 71 ATA He-O2 on organ blood flow in the rat

Cited by 10 publications

References 0 publications

Cardiovascular effects of hyperbaric oxygen with and without addition of carbon dioxide

Cardiovascular effects of hyperbaric oxygen with and without addition of carbon dioxide

Repeated normoxic hyperbaric exposures induce haemodynamic and myocardial changes in rats

Effects of SCH 42495, a neutral endopeptidase inhibitor, on cardiac function and mass in rats after repeated hyperbaric exposures

Contact Info

Product

Resources

About