Effect of chronic hypoxia on hemodynamics, organ blood flow and O2 supply in rats

Kuwahira, Ichiro; Heisler, N.; Piiper, Johannes; González, Norberto C.

doi:10.1016/0034-5687(93)90041-8

Cited by 33 publications

(30 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These findings are consistent with those made previously by ourselves and others (Kuwahira et al 1993;Mian & Marshall, 1996; Thomas & Marshall, 1997). The increase in Hct (from 42 YO in N rats to 57 YO in CH rats) and the accompanying increase in haemoglobin concentration (from -15.8 to 21.4 g dl-') was comparable to that reported in rats exposed to 10% 0, for 3 weeks (13.9 to 21.7 g dl-'; Kuwahira et al 1993). The consequence of these changes was that in the present study and in that of Kuwahira et al…”

Section: Chronically Hypoxic Ratssupporting

confidence: 83%

The effects of acute and chronic systemic hypoxia on muscle oxygen supply and oxygen consumption in the rat

Marshall¹,

Davies²

1999

Experimental Physiology

View full text Add to dashboard Cite

SUMMARYThe aims of the present study were to evaluate how acute systemic hypoxia affects 0, delivery to skeletal muscle and muscle 0, consumption (voJ of the rat and to establish how these relationships are altered by chronic systemic hypoxia. Thus, the effects of breathing different concentrations of 0, (air, 12 % and 8 % 0,) upon oxygen delivery and vo, were studied in hindlimb muscles of control, normoxic (N) rats and of rats that had been made chronically hypoxic in a chamber at 12 % 0, for 3-4 weeks (CH) rats. Under anaesthesia, arterial blood pressure, femoral blood flow (FBF), arterial 0, content (Ca,02) and venous 0, content in the efflux from hiindlimb were measured. In N rats, changing the inspirate from air to 12 YO and 8 % 0, for 5 min each, reduced C,,,? from 20 f 0.3 ml (100 ml)-' in air to 13 f 1.0 ml (100 ml)-' in 8 % 0,. FBF did not change significantly (1.7 f 0.1 ml m i d in air) so that 0, delivery to hindlimb muscles fell from 0.28 f 0.07 to 0.16 f 0.02 ml min-' in 8 % 0,. Nevertheless, the-??, of hindlimb muscles was well maintained: 0.06 & 0.02 ml min-' in air and 0.08 k 0.02 ml min in 8 % 0,. In CH rats breathing 12 % 0,, Ca,02 (23 f 1.0 ml (100 ml)-') was comparable to that of N rats breathing air, due to an increase in haematocrit, as were FBF (1.6 f 0.2 ml m i d ) and 0, delivery (0.39 f 0.05 ml min-').However, vo2 was 2.5-fold greater in CH rats (0.16 f 0.03 ml min-'). As in N rats, FBF was well maintained at 1.7 f 0.2 and 1.6 f 0.2 ml min-' in 8 % 0, and air, respectively. Further, 3 was also well maintained, at 0.17 f 0.02 and 0.12 f 0.02 ml min-' in 8 % 0, and air, respectively.These results suggest that, contrary to previous reports, muscle vo2 of the rat is independent of 0, delivery over a wide range of 0, delivery values. They also sugges: that muscle Vo, #of CH rats is similarly independent of 0, delivery. The novel finding that muscle Voz has a greater absolute value in CH rats can, we propose, be explained by an increase in voz of the vasculature rather than of the skeletal muscle fibres and reflects increased biosynthetic activity of the vessel walls and/or vascular remodelling. 0 2 .

show abstract

Section: Chronically Hypoxic Ratssupporting

confidence: 83%

The effects of acute and chronic systemic hypoxia on muscle oxygen supply and oxygen consumption in the rat

Marshall¹,

Davies²

1999

Experimental Physiology

View full text Add to dashboard Cite

show abstract

“…Finally, erythropoietin may have a direct growth effect on blood vessels and exacerbate systemic hypertension in already hypertensive animals (Gogusev et al 1994). In our model, IHX did not modify resting heart rate whereas in episodic hypoxia (sleep apnoea) this variable is increased (Fletcher, 2001) and it is unchanged or decreased in chronic hypoxia (Kuwahira et al 1993;Gonzalez et al 1998;Favret et al 2001). This result indicates that a longer exposure time to hypoxia, even with alternance in normoxia produced a cardiovascular pattern specific to our model of IHX switching towards a chronic pattern with respect to resting heart rate.…”

Section: R Gerrnak and Otherscontrasting

confidence: 48%

“…Acute and episodic hypoxia have been found to be associated with an increase in systemic blood pressure and resting heart rate (Fletcher, 2001). In chronic hypoxia, these parameters were unchanged or decreased in rats (Kuwahira et al 1993;Gonzalez et al 1998;Favret et al 2001) or slightly increased in humans (Richalet, 1990;Antezana et al 1992). In acute (days) and chronic hypoxia in vivo, the progressive blunting of the chronotropic responsiveness has been attributed to a decreased cardiac sensitivity to adrenergic stimulation (Richalet 1990;Antezana et al 1992) andlor an increased cholinergic activation of the heart (Hartley et al 1974;Selvamurthy et …”

mentioning

confidence: 99%

Effect of intermittent hypoxia on cardiovascular function, adrenoceptors and muscarinic receptors in Wistar rats

Germack

León‐Velarde

Barra

et al. 2002

Experimental Physiology

View full text Add to dashboard Cite

The usual model of intermittent hypoxia (sleep apnoea) corresponds to repeated episodes of hypoxia from a few seconds to a few hours interspersed with episodes of normoxia. The aim of this study was to evaluate in rats the effect of two periods of intermittent exposure for 2 months to hypoxia (IHX1,24 h in hypoxia (428 Torr), 24 h in normoxia; IHX2,48 h in hypoxia (428 Torr), 24 h in normoxia) as a new model of hypoxia simulating intermittent exposure to high altitude experienced by Andean miners. We assessed the haematological parameters, time course of resting heart rate and systolic blood pressure. We also evaluated the expression of adrenergic and muscarinic receptors. IHXl and IHX2 produced an increase in haematocrit, haemoglobin concentration and mean corpuscular volume as previously seen in most hypoxic models. IHXl and IHX2 induced a simiiar sustained elevation of systolic blood pressure (132 k 2 and 135 f 3 mmHg, respectively, vs. the control level of 121 & 16 mmHg) after I0 days of exposure without change in heart rate. Right ventricular (RV) hypertrophy (225 f 13 and 268 k 15 mg g-I, vs. 178 k 7 mg g-') and downregulation of a,-adrenoceptor (RV 127 k 21 and 94 k 16 fmol mg-' vs. 157 f 8 fmol mg-'; left ventricle (LV): 141 f 5 and 126 f 9 fmol mg-' vs. 152 f 5 fmol mg-') have been found in both groups, with right ventricular hypertrophy being greater and a,-adrenoceptor density being lower in IHX2 than in HX1 groups. These data indicate that both parameters are related to the time of exposure to hypoxia. IHXl and IHXZ produced the same magnitude of upregulation of muscarinic receptors (LV, 60%; RV, 40%), and no change in /3-adrenoceptors. In conclusion, exposure to intermittent hypoxia led to polycythaemia and RV hypertrophy as observed in other types of hypoxia. A specific cardiovascular response was seen, that is an increase in blood pressure without change in heart rate, which was different from the one observed in episodic and chronic hypoxia. Furthermore, this model involved specific modifications of a,-adrenergic and muscarinic expression. Expen 'mental Physiologv (2002) 87.4,453-460.

show abstract

“…These experiments underlined that the intermittent occurrence of hypoxia may be the main factor in the pathogenesis of stable HT. Continuous hypoxia causes vasodilation, not vasoconstriction [40,219], possibly explaining why stable HT is more common clinically in OSA patients than in patients with chronic pulmonary disease [211].…”

Section: Systemic Arterial Pressure (Fig 6)mentioning

confidence: 99%

The cardiovascular effects of obstructive sleep apnoeas: analysis of pathogenic mechanisms

Mr¹,

Marrone²,

Insalaco³

et al. 1994

Eur Respir J

132

View full text Add to dashboard Cite

Effect of chronic hypoxia on hemodynamics, organ blood flow and O2 supply in rats

Cited by 33 publications

References 12 publications

The effects of acute and chronic systemic hypoxia on muscle oxygen supply and oxygen consumption in the rat

The effects of acute and chronic systemic hypoxia on muscle oxygen supply and oxygen consumption in the rat

Effect of intermittent hypoxia on cardiovascular function, adrenoceptors and muscarinic receptors in Wistar rats

The cardiovascular effects of obstructive sleep apnoeas: analysis of pathogenic mechanisms

Contact Info

Product

Resources

About