Support of arterial blood pressure by major pressor systems in conscious dogs

Brand, Paul H.; Metting, Patricia J.; Britton, Steven L.

doi:10.1152/ajpheart.1988.255.3.h483

Cited by 17 publications

(11 citation statements)

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“…Although we did not observe any significantly decreased tolerance to blood loss after captopril treatment alone, the effect of combined treatment with AVP-ANT and captopril indicates that the renin-angiotensin system is of importance for the maintenance of blood pressure during haemorrhage also in conscious sheep. Whether this is only evident when the effects of AVP and/or the autonomic nervous system are interfered with remains to be shown, but it is partly supported by results from studies on blood pressure regulation after captopril treatment during autonomic blockade in dogs (Brand et al 1988).…”

Section: Discussionmentioning

confidence: 98%

“…In the latter study angiotensin converting enzyme inhibition with teprotide was also without effect on the cardiovascular response to rapid removal of 10% of the estimated blood volume. Whether this is only evident when the effects of AVP and/or the autonomic nervous system are interfered with remains to be shown, but it is partly supported by results from studies on blood pressure regulation after captopril treatment during autonomic blockade in dogs (Brand et al 1988). Although we did not observe any significantly decreased tolerance to blood loss after captopril treatment alone, the effect of combined treatment with AVP-ANT and captopril indicates that the renin-angiotensin system is of importance for the maintenance of blood pressure during haemorrhage also in conscious sheep.…”

Section: Discussionmentioning

confidence: 99%

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Tolerance to haemorrhage during vasopressin antagonism and/or captopril treatment in conscious sheep

Ullman

Hjelmqvist

Lundberg

et al. 1992

Acta Physiologica Scandinavica

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The effect of separate and combined blockade of vasopressin (AVP) V1-receptors and angiotensin II formation on resistance to a slow venous haemorrhage (0.7 ml kg-1 min-1) was studied in six conscious adult sheep by bleeding to the point of an abrupt fall in the mean systemic arterial pressure (MSAP). Intravenous administration of the V1-receptor antagonist [d(CH2)5Tyr(Me)AVP] (10 micrograms kg-1) and/or the angiotensin I converting enzyme inhibitor captopril (20 mg + 1 mg h-1) did not cause any significant haemodynamic changes in the normovolaemic animal. The volume of haemorrhage necessary to induce acute hypotension (MSAP < 50 mmHg) was significantly smaller after AVP blockade alone (13.8 +/- 0.7 ml kg-1; P < 0.01) but not after captopril treatment (14.7 +/- 1.6 ml kg-1; n.s.) compared to control animals receiving no drug treatment (16.8 +/- 0.6 ml kg-1). The combined treatment with the AVP antagonist and captopril caused a further decrease in tolerance to haemorrhage (9.4 +/- 1.2 ml kg-1; P < 0.001). Blockade of AVP V1-receptors was associated with an attenuated increase in systemic vascular resistance immediately after the end of haemorrhage, concomitant with an accentuated lowering of the central venous pressure. In contrast, captopril treatment decreased the degree of vasoconstriction mainly during the second half of the posthaemorrhage observation period of 1 hour. It is concluded that both AVP and angiotensin II contribute to the maintenance of the MSAP during haemorrhage in conscious sheep.(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Tolerance to haemorrhage during vasopressin antagonism and/or captopril treatment in conscious sheep

Ullman

Hjelmqvist

Lundberg

et al. 1992

Acta Physiologica Scandinavica

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“…Haemorrhage causes marked autonomic activation as well as the release of renin and vasopressin (Brand et al 1988). Thus, the exaggerated increase in power observed in haemorrhaged SHR was reduced by each of the blockers.…”

Section: Discussionmentioning

confidence: 99%

Effect of Haemorrhage on the Power of Low Frequency Blood Pressure Fluctuations in Young Spontaneously Hypertensive Rats

Eliash

Akselrod

et al. 1995

Clin Exp Pharma Physio

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1. Before the onset of hypertension low frequency (0.04-0.1 Hz) MAP fluctuations are reduced in SHR when compared to WKY. We studied the effect of haemorrhage under (YI blockade or angiotensin converting enzyme inhibition (CEI) on the power spectra (PS) of each strain.2. MAP was recorded from the caudal artery in conscious, 1 month old SHR and WKY. Three groups of rats were studied. Group 1, acute 2 mL haemorrhage; groups 2 and 3, injection of prazosin (0.25-2.5 mg/kg) or captopril(O.5-4 mg/kg), followed by haemorrhage, as in group 1. The PS was divided into 3 frequency bands, 0.004-0.04,0.04-0.07 and 0.07-0.1 Hz.3. In SHR, although the baseline MAP levels were similar to those of WKY, the PS was significantly damped in each of the 3 frequency bands.4. Haemorrhage induced a similar MAP fall in both strains accompanied by an increase in the slow MAP fluctuations. However, in SHR the PS response was significantly greater than in WKY. The biggest response was in the slowest (0.004-0.04 Hz) frequency band, 8.7f 1.7 vs 1.5f 0.4 times baseline levels, respectively. 5. The difference between the two strains in the PS response to haemorrhage was eliminated by a1 blockade. The exaggerated response observed in haemorrhaged, unblocked SHR was reduced in the 3 frequency bands.6. Captopril reduced the PS response to haemorrhage in SHR to the level observed in WKY in all 3 frequency bands.7. The enhanced amplification of the MAP fluctuations in haemorrhaged SHR may indicate that SHR requires greater recruitment of control mechanisms than WKY to maintain MAP at a similar level to WKY.

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“…Wagner, et al (1996) proposed that other effectors of BP will compensate this loss of control (Brand, et al, 1988), hence, perturbing the dynamics of the regulating system in a way that is simpler and less complex.…”

Section: Experimental Condition (Number Of Animals)mentioning

confidence: 99%

Deterministic chaos in blood pressure signals during different physiological conditions

Kinnane

Ringwood

Ramchandra

et al. 2003

IFAC Proceedings Volumes

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Several coupled and nonlinear controlling mechanisms are involved in the regulation of blood pressure. The possible presence of chaos in physiological signals has been the subject of some research. In this study, blood pressure signals were analysed using a range of nonlinear time series analysis techniques. Individual effectors of blood pressure were either experimentally removed or enhanced, so that the controlling mechanisms that are responsible for the chaotic nature of the signals may be identified by chaotic analysis of the signals. The level of chaos varied across the different experimental conditions, showing a distinct decrease from control conditions to all other experimental conditions.

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Support of arterial blood pressure by major pressor systems in conscious dogs

Cited by 17 publications

References 0 publications

Tolerance to haemorrhage during vasopressin antagonism and/or captopril treatment in conscious sheep

Tolerance to haemorrhage during vasopressin antagonism and/or captopril treatment in conscious sheep

Effect of Haemorrhage on the Power of Low Frequency Blood Pressure Fluctuations in Young Spontaneously Hypertensive Rats

Deterministic chaos in blood pressure signals during different physiological conditions

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