Effect of volume expansion on pressor response to angiotensin II in pregnant ewes.

S. Matsuura, R. P. Naden, N. F. Gant, C. R. Parker, C. R. Rosenfeld

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Vascular refractoriness to infused angiotensin II (AII) characterizes normal human and ovine pregnancy. To ascertain whether the refractoriness in the gravid ewe is mediated by either endogenous plasma concentrations of renin and AII or vasomotor reflexes, effects of acute volume expansion (VE) on the pressor response to AII were studied in chronically instrumented nonpregnant and near-term pregnant sheep. Dose-response curves describing the pressor response (delta BP) were determined before and after infusions of 1.0 1 of isotonic saline (NS) or 0.5 1 of 10% dextran (D). In nonpregnant sheep, hematocrit (Hct) and plasma renin activity (PRA) fell in all animals after NS (n = 7) and D (n = 6) (P less than 0.005). After VE with NS and D, delta BP increased at each dose of AII (P less than 0.05). The pressor response to AII in pregnant sheep was not altered by NS although decreases in Hct and PRA were comparable to those in nonpregnant sheep. Baroreceptor responses were not altered. Vascular refractoriness to infused AII in pregnant sheep is not due primarily to changes in plasma concentrations of renin-AII but more likely to another factor, vessel wall refractoriness. In this respect, the ewe is similar to the human.

Original languageEnglish (US)
JournalThe American journal of physiology
Volume240
Issue number6
StatePublished - Jun 1981

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Angiotensin II
Sheep
Renin
Hematocrit
Blood Vessels
Pressoreceptors
Reflex
Pregnancy

ASJC Scopus subject areas

  • Medicine(all)

Cite this

Matsuura, S., Naden, R. P., Gant, N. F., Parker, C. R., & Rosenfeld, C. R. (1981). Effect of volume expansion on pressor response to angiotensin II in pregnant ewes. The American journal of physiology, 240(6).

Effect of volume expansion on pressor response to angiotensin II in pregnant ewes. / Matsuura, S.; Naden, R. P.; Gant, N. F.; Parker, C. R.; Rosenfeld, C. R.

In: The American journal of physiology, Vol. 240, No. 6, 06.1981.

Research output: Contribution to journalArticle

Matsuura, S, Naden, RP, Gant, NF, Parker, CR & Rosenfeld, CR 1981, 'Effect of volume expansion on pressor response to angiotensin II in pregnant ewes.', The American journal of physiology, vol. 240, no. 6.
Matsuura, S. ; Naden, R. P. ; Gant, N. F. ; Parker, C. R. ; Rosenfeld, C. R. / Effect of volume expansion on pressor response to angiotensin II in pregnant ewes. In: The American journal of physiology. 1981 ; Vol. 240, No. 6.
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