Age‐Dependent Effects of Captopril on the Arterial Baroreflex Control of Heart Rate in Conscious Lambs

Monument, Michael J.; Smith, Francine G.

doi:10.1113/eph8802602

Cited by 15 publications

(25 citation statements)

References 63 publications

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“…During the perinatal period, the renin-angiotensin system is activated, with increased plasma renin activity and plasma ANG II levels before birth and further increases after the transition to newborn life [4,16,22,31]. As postnatal maturation proceeds, plasma renin activity and plasma ANG II levels decline [4,16,22,31].…”

Section: Introductionmentioning

confidence: 99%

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Systemic and renal hemodynamic effects of the AT1 receptor antagonist, ZD 7155, and the AT2 receptor antagonist, PD 123319, in conscious lambs

Chappellaz

Smith

2006

Pflugers Arch - Eur J Physiol

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Experiments were carried out to investigate age- and dose-dependent effects of the selective AT(1) receptor antagonist, ZD 7155, and the selective AT(2) receptor antagonist, PD 123319, on systemic and renal hemodynamics in conscious, chronically instrumented lambs aged approximately 1 and approximately 6 weeks of postnatal life. Mean arterial pressure (MAP), mean venous pressure (MVP), and renal blood flow (RBF) were measured for 10 min before and for 120 min after ZD 7155, PD 123319, or vehicle. In both age groups, administration of ZD 7155 decreased renal vascular resistance (RVR) and increased RBF within 5 min. These responses lasted less than 90 min but were not dose-dependent. MAP decreased by 30 min after administration of ZD 7155 in both age groups at doses >/=400 microg kg(-1); the remaining decreased for up to 120 min, depending upon the dose. Pressor responses to angiotensin II (ANG II) were abolished within 5 min of administration of all doses of ZD 7155, at both 1- and 6 weeks. PD 123319 had no detectable effects on systemic or renal hemodynamics or on the pressor responses to ANG II. Therefore, under physiological conditions in conscious newborn animals, ANG II modulates both resting blood pressure and RVR through activation of AT(1) but not AT(2) receptors.

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Section: Introductionmentioning

confidence: 99%

“…As postnatal maturation proceeds, plasma renin activity and plasma ANG II levels decline [4,16,22,31]. The expression of AT 1 and AT 2 receptors is also developmentally regulated, AT 2 receptors predominating in the brain, adrenal gland, and kidney of fetal and newborn rats, fowl, rabbits, sheep, and humans [1,2,5,7,11,13,15,24,25,32].…”

Section: Introductionmentioning

confidence: 99%

Systemic and renal hemodynamic effects of the AT1 receptor antagonist, ZD 7155, and the AT2 receptor antagonist, PD 123319, in conscious lambs

Chappellaz

Smith

2006

Pflugers Arch - Eur J Physiol

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“…This is evidenced by increased plasma renin activity and plasma AngII levels prior to birth and further increases after birth (8)(9)(10). However, as postnatal maturation proceeds and the kidneys of the newborn undergo major structural and functional changes in order to assume responsibility for the regulation of extracellular fluid volume homeostasis and arterial pressure, plasma renin activity and circulating AngII levels progressively decline (8)(9)(10). Furthermore, AT 1 R and AT 2 R expression within the kidney is developmentally regulated.…”

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confidence: 99%

Reduced sensitivity of the renal vasculature to angiotensin II in young rats: the role of the angiotensin type 2 receptor

et al. 2014

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Background:The angiotensin type-2 receptor (AT 2 R) opposes the vasoconstrictor actions of angiotensin II (AngII) mediated through the angiotensin type-1 receptor (AT 1 R). Renal AT 2 R levels are high during fetal life, but decrease significantly during postnatal maturation. To provide insight into the functional role of the AT 2 R in the kidney during postnatal development, we investigated the effects of AT 2 R antagonism on cardiovascular responses to AngII in young and adult male rats. Methods: In anesthetized 3-and 6-wk-old male SpragueDawley rats, mean arterial pressure (MAP) and renal blood flow (RBF) were measured in response to AngII in the presence of vehicle treatment or AT 2 R blockade with PD123319. results: The pressor effect of AngII and associated reduction in RBF were significantly less in 3-wk-than 6-wk-old rats. AT 2 R blockade potentiated the reduction in RBF in response to AngII in 3-wk-old rats only. conclusion: In young rats, the AT 2 R modulates the response to AngII, blunting renal vasoconstriction. This effect is attenuated with age in association with a developmental reduction in renal AT 2 R expression. These findings may have implications for the development of novel therapies that target the reninangiotensin system for the improvement of renal function in term and, in particular, preterm infants.

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“…During the perinatal period, the renin-angiotensin system is activated, with increased levels of renin and ANG II present in the newborn of all species studied to date, including the human infant [3,7,20,25,43] although the physiological relevance of this is not known.…”

Section: Introductionmentioning

confidence: 99%

Haemodynamic responses to angiotensin II in conscious lambs: role of nitric oxide and prostaglandins

Ebenezar

Wong

Smith

2011

Pflugers Arch - Eur J Physiol

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It was hypothesized that nitric oxide (NO) and prostaglandins (PGs) play a synergistic role in modulating haemodynamic responses to angiotensin II (ANG II) in an age-dependent manner. To this end, experiments were carried out in conscious, chronically instrumented lambs aged ∼1 week (N = 9) and ∼6 weeks (N = 10) to evaluate the haemodynamic responses to ANG II, before and after treatment with the L: -arginine analogue, N-nitro-L: -arginine methyl ester (L: -NAME), as well as the cyclooxygenase inhibitor, indomethacin (INDO). Pressor and renal blood flow responses to ANG II were measured before (control) and after administration of L: -NAME (20 mg kg(-1)), following pretreatment with either vehicle (VEH) (experiment 1) or INDO (1 mg kg(-1), experiment 2). The two experiments were carried out at minimum intervals of 48 h. In both age groups, the pressor and renal vasoconstrictor responses to ANG II were augmented by pretreatment with INDO, the effects being similar at 1 and 6 weeks. The haemodynamic responses to ANG II were, however, not altered after L: -NAME following pretreatment with either VEH or INDO. These data provide new evidence that soon after birth, endogenously produced PGs, but not endogenously produced NO, balance the vasoconstrictor actions of ANG II. There is, however, no apparent interaction between PGs and NO in modulating the responses to ANG II postnatally.

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Age‐Dependent Effects of Captopril on the Arterial Baroreflex Control of Heart Rate in Conscious Lambs

Cited by 15 publications

References 63 publications

Systemic and renal hemodynamic effects of the AT1 receptor antagonist, ZD 7155, and the AT2 receptor antagonist, PD 123319, in conscious lambs

Systemic and renal hemodynamic effects of the AT1 receptor antagonist, ZD 7155, and the AT2 receptor antagonist, PD 123319, in conscious lambs

Reduced sensitivity of the renal vasculature to angiotensin II in young rats: the role of the angiotensin type 2 receptor

Haemodynamic responses to angiotensin II in conscious lambs: role of nitric oxide and prostaglandins

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