Major and collateral components of blood flow to pregnant sheep uterus

Eo, Fuller; Pm, Galletti; Takeuchi, Taro

doi:10.1152/ajplegacy.1975.229.2.279

Cited by 35 publications

(16 citation statements)

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“…We examined the effects of the ovarian cycle and pregnancy status on the vessel external diameter measured at multiple sites (8)(9)(10)(11)(12) along the length of each artery (Table 1). In the four reproductive treatment groups, the external diameter decreased progressively from the II to UA 3°(P Ͻ 0.001).…”

Section: Resultsmentioning

confidence: 99%

“…RA, internal iliac arteries (II), and UA [primary (UA 1°), secondary (UA 2°), and tertiary (UA 3°) branches] were dissected free of connective tissue, fat, and veins and then rinsed free of blood in phosphate-buffered saline (8 mM sodium phosphate, 2 mM potassium phosphate, and 0.15 M NaCl, pH 7.4; Sigma; St. Louis, MO). The external diameter (in mm) of each artery was measured at multiple sites (8)(9)(10)(11)(12) along the length of the artery using a micrometer. The arteries were then opened longitudinally, and the endothelium/tunica intima was gently scraped (4-6 times) from the artery using a curvedend spatula and placed directly in lysis buffer (50 mM Tris, 0.15 M NaCl, and 10 mM EDTA, pH 7.4, plus the addition of 0.1% Tween 20, 0.1% ␤-mercaptoethanol, 0.1 M phenylmethylsulfonyl fluoride, 5 g/ml leupeptin, and 5 g/ml aprotinin; all from Sigma).…”

Section: Methodsmentioning

confidence: 99%

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Endothelial vasodilator production by uterine and systemic arteries. IX. eNOS gradients in cycling and pregnant ewes

Joyce

Phernetton

Shaw

et al. 2002

American Journal of Physiology-Heart and Circulatory Physiology

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The follicular phase (FOL) and pregnancy exhibit increases in uterine blood flow (UBF), estrogen levels, and uterine artery (UA) endothelial nitric oxide synthase (eNOS) expression. UA branching within the mesometrium increases the total vascular cross-sectional area, which reduces the vascular perfusion pressure gradient, thus locally decreasing the blood flow velocity. Shear stress (SS) activates eNOS and may be associated with UBF elevations during FOL and pregnancy. We hypothesized that regional differences in eNOS responses are observed with both decreases in vessel diameter and during the ovarian cycle and pregnancy. Endothelial isolated proteins were collected from renal (RA) and internal iliac arteries (II) as well as from primary (UA 1°), secondary (UA 2°), and tertiary (UA 3°) UA branches of nonpregnant luteal phase (LUT; n ϭ 6) and FOL (n ϭ 6) as well as midpregnant (MP; 82 Ϯ 1 days gestation, n ϭ 6) and late pregnant (LP; 127 Ϯ 3 days gestation, n ϭ 6) ewes (term ϭ 145 Ϯ 3 days gestation) for Western blot analysis. LUT RA, II, and UA 1°eNOS levels were similar. There was a 60.7 Ϯ 9.8% reduction in eNOS expression in UA 2°and UA 3°. A similar decreasing eNOS regional expression gradient was observed in LP ewes. No eNOS regional expression gradient was observed in FOL or MP ewes because eNOS increased in UA 2°and UA 3°. In UA 2°and UA 3°, MP Ͼ LP ϭ FOL Ͼ LUT. Thus, with increasing UBF, FOL and pregnancy rises in SS may regulate eNOS protein expression in smaller diameter UAs. A decrease in LUT and LP UA 2°and UA 3°endothelial eNOS suggest a possible negative feedback mechanism due to downregulation of eNOS if SS is normalized. uterus; shear stress; endothelial nitric oxide synthase; ovarian; estrogen; progesterone UTERINE ARTERY (UA), but not systemic (renal) artery (RA) endothelial, endothelial nitric oxide (NO) synthase (eNOS) protein (29, 40) and mRNA (29) are elevated during the follicular phase of the ovarian cycle, in which the endogenous estrogen-to-progesterone ratio and uterine blood flow (UBF) are elevated (9, 11, 26). A low basal UBF level and a low estrogen-toprogesterone ratio characterize the luteal phase. Similar increases in eNOS protein levels were noted during the follicular phase of the menstrual cycle in women (31). Furthermore, these alterations in eNOS levels in the UA endothelium can be mimicked by exogenous administration of 17␤-estradiol and/or progesterone (35,36,40). [27][28][29]37,47) and its physiological second messenger cGMP (17,27,37) are increased during pregnancy. UA, but not systemic artery endothelial, eNOS protein (28,29,31,47) and mRNA (1, 29) expression and activity (27,31,46) also are elevated by pregnancy. UA eNOS protein levels are unchanged during late gestation, from day 110 to 142 of ovine pregnancy (28), although nitrite or nitrate (NO x ) levels increase with advancing gestational ages during the third trimester (29). The timing of either the gestational increase in UA eNOS expression or the circulating NO x levels during the second trimester of pregnanc...

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Endothelial vasodilator production by uterine and systemic arteries. IX. eNOS gradients in cycling and pregnant ewes

Joyce

Phernetton

Shaw

et al. 2002

American Journal of Physiology-Heart and Circulatory Physiology

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“…It has previously been studied in rats, 19 guinea pigs, 20 and ewes. 21 During pregnancy, blood flow through the uterine circulation increases substantially. 22,23 To accommodate this increase in uterine blood flow, the uterine vasculature undergoes luminal expansion and an increase in wall mass, 19 a process termed outward hypertrophic remodeling or arteriogenesis.…”

mentioning

confidence: 99%

Uterine Artery Structural and Functional Changes During Pregnancy in Tissue Kallikrein–Deficient Mice

Hilgers

Bergaya

Schiffers

et al. 2003

ATVB

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Objective-Tissue kallikrein (TK) participates in acute flow-induced dilatation (FID) of large arteries. We investigated whether TK deficiency blunts FID and alters chronic flow-related arterial structural and functional changes in resistance-sized muscular arteries. Methods and Results-Vasomotor responses and structural parameters were determined in uterine arteries isolated from nonpregnant, 18-to 19-day pregnant, and 7-day postpartum TK Ϫ/Ϫ and TK ϩ/ϩ littermate mice. In TK Ϫ/Ϫ mice, values of diameter, medial cross-sectional area (CSA), myogenic tone, and dilatation in response to acetylcholine were comparable to those values in TK ϩ/ϩ mice, but FID (0 to 100 L/min) was significantly reduced (55Ϯ4% versus 85Ϯ4% in TK ϩ/ϩ mice). In both mouse strains, pregnancy resulted in significant increases in diameter and medial CSA and in the N w -nitro-L-arginine methyl ester-sensitive component of FID. By 7 days after pregnancy, uterine arterial diameter and CSA values no longer differed from nonpregnant values, and FID was markedly reduced in TK Ϫ/Ϫ and TK ϩ/ϩ mice. Conclusions-These observations (1) confirm at the level of resistance arteries the key role of TK in FID and (2) Pressure and flow are hemodynamic determinants of circumferential wall stress and wall shear stress (WSS) in the arterial system. On an acute basis, they modulate arterial smooth muscle tone: an increase in transmural pressure triggers a myogenic contractile response, 6 -8 whereas an increase in flow induces an endothelium-dependent FID. 8 -11 Long-term changes in blood flow lead to arterial structural adaptations to normalize WSS. [12][13][14][15][16][17] In general, chronic blood flow elevations lead to a widening of lumen diameter, whereas sustained reductions in blood flow lead to a narrowing of lumen diameter. These structural arterial adaptations have been shown to be endothelium dependent. 18 Pregnancy may be considered a model of physiological flow-related remodeling of uterine arteries. It has previously been studied in rats, 19 guinea pigs, 20 and ewes. 21 During pregnancy, blood flow through the uterine circulation increases substantially. 22,23 To accommodate this increase in uterine blood flow, the uterine vasculature undergoes luminal expansion and an increase in wall mass, 19 a process termed outward hypertrophic remodeling or arteriogenesis. The driving force for this remodeling is increased WSS. Previous studies have demonstrated that chronic elevations in blood flow lead to an upregulation of FID, which is mainly due to an enhanced production of endothelial factors, such as NO and prostaglandins.The purpose of the present study was to investigate whether TK deficiency alters FID and chronic flow-related arterial structural and functional alterations in resistance-sized muscular arteries. Vasomotor responses and structural parameters were determined in uterine arteries isolated from nonpregnant, latepregnant, and postpartum TK Ϫ/Ϫ and TK ϩ/ϩ mice. Methods Mice Lacking TKTK-null mice were obtained by targeted disruption of the...

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“…After traveling for about 3 -4 cm along the edge of the uterine horn, each main artery gives a major branch called the middle uterine artery and a smaller one termed the dorsal uterine artery. The former supplies most of the uterine fundus while the latter nourishes the lower uterine segment, the cervix, the bladder and the upper part of the vagina (8).…”

Section: A Natornical a Spectsmentioning

confidence: 99%

“…In essence the blood How of the common in ternal iliac artery is largely destined to supply the uterus (fundus of both horns and the cer vix), the bladder and vagina through both the middle and dorsal uterine arteries (8). Only a small fraction of the common internal iliac flow diverted through the medial sacral artery nourishes nongenital areas.…”

Section: A Natornical a Spectsmentioning

confidence: 99%

Hemodynamic Responses of the Pelvic Vascular Bed to Vasoactive Stimuli in Pregnant Sheep

Tabsh¹,

Nuwayhid²,

Erkkola³

et al. 1981

Neonatology

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The responses of the common internal iliac artery and middle uterine artery of the pregnant horn to continuous infusions of graded doses of norepinephrine, epinephrine, dopamine, isoxsuprine, angiotensin and nitroprusside were investigated in chronically instrumented pregnant ewes. Norepinephrine progressively decreased the blood flow and increased the resistance in both vessels but the changes were more marked in the middle uterine artery. Isoxsuprine and epinephrine had an insignificant effect on the common internal iliac artery blood flow, but decreased that of the middle uterine artery. Nitroprusside decreased the flow in both vessels proportionately. Angiotensin in doses less than 0.16 µg/kg/min increased the flow in both arteries to the same extent, but higher doses decreased both flows. It is concluded that in the chronically instrumented pregnant ewe, the responses of contiguous vascular beds to different vasoactive agents may differ depending on the nature of the stimulus.

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Major and collateral components of blood flow to pregnant sheep uterus

Cited by 35 publications

References 0 publications

Endothelial vasodilator production by uterine and systemic arteries. IX. eNOS gradients in cycling and pregnant ewes

Endothelial vasodilator production by uterine and systemic arteries. IX. eNOS gradients in cycling and pregnant ewes

Uterine Artery Structural and Functional Changes During Pregnancy in Tissue Kallikrein–Deficient Mice

Hemodynamic Responses of the Pelvic Vascular Bed to Vasoactive Stimuli in Pregnant Sheep

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