The differential effects of prazosin and hydralazine on sympathoadrenal activity in conscious rats

Tk, Keeton; Am, Biediger

doi:10.1016/0014-2999(89)90255-0

Cited by 13 publications

(7 citation statements)

References 21 publications

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“…Prazosin also increased this HF SBP component as previously reported by our group (Japundzic et al, 1991) and others (Gonzalez Gonzalez et al, 1995). This effect of prazosin might reflect a venodilator effect of the drug, in addition to its arterial vasodilating action (Bolt and Saxena, 1984;Keeton and Biediger, 1989). The high level of HF S B P component reached after prazosin treatment could be the reason, through a ceiling effect, for the absence of any further HF increase after hemorrhage in these rats treated with the a, -adrenoceptor antagonist.…”

Section: Discussionmentioning

confidence: 95%

Effects of graded hemorrhage on short‐term variability of blood pressure in conscious rats

Baujard

Ponchon

1996

Fundamemntal Clinical Pharma

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A controlled graded bleeding was performed in conscious rats with 15 min intervals between two withdrawals, in order to induce a 25% blood loss without hypotension. Heart rate (HR) was unaffected as well. The spectral profiles of systolic blood pressure (SBP) analyzed on 51.2 s segments exhibited increases in the high frequency (HR, respiratory) component. This increase paralleled the blood loss with a rise ranging from 20% for a 1 mL/kg hemorrhage to 90% for a 11 mL/kg removal. These changes were associated with increases in the mid-frequency (MF, Mayer waves) component of SBP variability. These latter rises were between 30 and 40% of the control value. Breathing frequency (BF) and blood gases were unaltered following hemorrhage. A shift of fluid occurred during the 3 h session as reflected by the significant hemodilution. Rats were also bled after pretreatment with prazosin (1 mg/kg) or with an association of prazosin (1 mg/kg) and losartan (10 mg/kg). These treatments increased HR. A marked fall in SBP occurred with the double blockade. Hemorrhage determined a relative bradycardia together with the SBP decrease (reversible shock) after prazosin and losartan treatment. Prazosin determined opposite changes in MF (-33%) and HF (+58%) SBP components. A further decrease in the MF SBP component was observed following the double blockade. Spectral profiles following hemorrhage were unchanged compared to the prehemorrhage blocked levels. Therefore graded nonhypotensive, ie, normotensive hemorrhage in rats, was associated with progressive increases in the respiratory SBP variations, estimated from the SBP spectrum. This sensitive index could reflect the low preload state due to hypovolemia. The hemorrhage-induced MF SBP component increase could reflect an increased sympathetic vasomotor drive, prevented with prazosin, as a reflex adjustment to hypovolemia. Renin activation could also contribute to the genesis of MF waves and its role in maintaining BP following hemorrhage was exemplified with alpha 1-adrenoceptor blockade.

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Section: Discussionmentioning

confidence: 95%

Effects of graded hemorrhage on short‐term variability of blood pressure in conscious rats

Baujard

Ponchon

1996

Fundamemntal Clinical Pharma

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“…Moreover, the ␣-adrenergic blocking effect of prazosin results in a dose-dependent compensatory increase of sympathoadrenal activity measured as elevated plasma epinephrine and norepinephrine concentrations (25). The sympathoadrenal activity continues to be elevated during chronic treatment (25), and therefore, it can be used as a marker of the ␣-adrenergic blocking effect of prazosin.…”

Section: Discussionmentioning

confidence: 99%

“…The sympathoadrenal activity continues to be elevated during chronic treatment (25), and therefore, it can be used as a marker of the ␣-adrenergic blocking effect of prazosin. Since we removed prazosin from the drinking water 41-42 h prior to the HIEC, the acute effect on the cardiovascular system and any changes in blood flow would have subsided (3).…”

Section: Discussionmentioning

confidence: 99%

Increased skeletal muscle capillarization enhances insulin sensitivity

Åkerström

Laub

Vedel

et al. 2014

American Journal of Physiology-Endocrinology and Metabolism

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“…A three-step study was designed. 1) The physiology of NE kinetics in the rat remains poorly known; previous studies have dealt with NE kinetics in controls or in response to antihypertensive drugs in spontaneously hypertensive rats (10,21,22). Our working hypothesis was to consider that NE kinetics should be in agreement with a high sympathetic drive in the rodent (28,34,36).…”

mentioning

confidence: 99%

Norepinephrine kinetics in freely moving rats

Maignan

Legrand

Aboulfath

et al. 2001

American Journal of Physiology-Endocrinology and Metabolism

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Norepinephrine (NE) kinetics were investigated in freely moving (FM) and minimally stressed (MS) rats with the isotope dilution technique. 1) The mean NE spillover rate (NE-SOR) was 79 +/- 6 ng. kg(-1). min(-1), and the mean NE metabolic clearance rate (NE-MCR) 179 +/- 9 ml. kg(-1). min(-1) (n = 31). Thus the NE kinetics in FM and MS rats are much faster than in human beings, probably related to a higher sympathetic drive. 2) Whether the magnitude of NE-MCR is related to the level of plasma NE concentration was investigated. No significant correlation was calculated between plasma NE concentration and NE-MCR in 31 control rats. When plasma NE concentration was varied during either acute or chronic infusion of exogenous NE, NE-MCR remained unchanged as long as animal hemodynamics were not altered. When plasma NE concentration was high enough to increase mean arterial pressure (MAP), NE-MCR was decreased. However, when MAP was increased within comparable magnitude, NE-MCR was decreased during NE and increased during epinephrine (Epi) infusion. Thus the existence of an alpha-/beta-adrenergic mechanism involved in the regulation of NE-MCR independent of known hemodynamic mechanisms is suggested. 3) The "epinephrine hypothesis" was revisited in FM and MS rats. At variance with humans, very high plasma Epi concentrations have to be induced to increase NE-SOR in resting rats. Furthermore, NE-MCR was also increased, accounting for the nonsignificant increase of plasma NE concentration. Within the range of Epi concentrations with no effect on NE-SOR, an increase of NE release was revealed when the presynaptic alpha(2)-adrenoreceptors were partially inhibited by yohimbine. This suggests the existence of a second epinephrine hypothesis.

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The differential effects of prazosin and hydralazine on sympathoadrenal activity in conscious rats

Cited by 13 publications

References 21 publications

Effects of graded hemorrhage on short‐term variability of blood pressure in conscious rats

Effects of graded hemorrhage on short‐term variability of blood pressure in conscious rats

Increased skeletal muscle capillarization enhances insulin sensitivity

Norepinephrine kinetics in freely moving rats

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