Differential development of umbilical and systemic arteries. II. Contractile proteins

Arens, Yvonne; Chapados, Rene; Cox, Blair E.; Kamm, Kristine E.; Rosenfeld, Charles R.

doi:10.1152/ajpregu.1998.274.6.r1815

Cited by 24 publications

(53 citation statements)

References 37 publications

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“…In general, this is dependent upon a variety of maturational changes in vascular function and reactivity, which may include changes in VSM contractile protein expression, ion channel expression and function, endothelial function, and receptor expression. For example, VSM contractile protein expression is developmentally regulated and appears to modify vascular responses in fetal and newborn sheep (34). Although the RAS is considered an important determinate of fetal and neonatal blood pressure through the effects of ANG II, AT receptor subtype expression in VSM from fetal and neonatal sheep also is developmentally regulated, and predominance of the adult AT 1 is not evident until Ͼ2 wk postnatal (18,19,35).…”

Section: Discussionmentioning

confidence: 99%

Differential Responses to Systemic and Local Angiotensin II Infusions in Conscious Postnatal Sheep

Velaphi

2002

Pediatric Research

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vascular smooth muscle until 2 wk postnatal when they are replaced by AT 1 . Thus, the mechanisms whereby ANG II increases MAP after birth are unclear. We examined the effects of ANG II on femoral vascular resistance (FmVR) and blood flow (FmBF) in serial studies of newborn sheep (n ϭ 7) at 7-14 d, 15-21 d, and 22-35 d. Animals had femoral catheters implanted for systemic ANG II infusions and cardiovascular monitoring, and a flow probe was implanted on the contralateral artery proximal to the superficial saphenous artery, which contained a catheter for intra-arterial ANG II infusions. Studies were performed using a range of systemic and intra-arterial ANG II doses. Systemic ANG II increased MAP dose-dependently at all ages (p Ͻ 0.001); however, responses were not age dependent. FmBF rose dose dependently at 7-14 d (p Ͻ 0.001) and was unchanged at older ages. The transition from fetal to newborn life is associated with numerous hemodynamic changes, including alterations in HR, blood pressure, PVR, and the distribution of cardiac output (1-4). The autonomic nervous system and the reninangiotensin system (RAS) are considered important modulators of the cardiovascular changes in the perinatal period. This is supported by evidence of increased circulating levels of catecholamines and ANG II during and after parturition (1, 4 -6). ANG II is the predominant vasoactive agent associated with the RAS and is believed to be an important regulator of blood pressure in fetal, neonatal, and adult sheep (7-9). The effects of ANG II on blood pressure may reflect its direct action on VSM through increases in PVR or on cardiac output by increasing venous return or HR (4, 10 -13). Indirect effects on VSM also may occur through activation of central autonomic nervous system activity or the release of other vasoactive mediators (11, 14 -16).ANG II mediates its actions by binding to specific AT. At least two AT subtypes have been identified, AT 1 and AT 2 , and their expression is developmentally regulated (17)(18)(19). In the adult, the AT 1 is the primary subtype expressed in most tissues, including VSM, and accounts for most biologic actions of ANG II (20,21). However, AT 2 are found in selective adult tissues, e.g. adrenal, myometrium, and uterine arteries from pregnant and nonpregnant women and sheep (9,(21)(22)(23)

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Section: Discussionmentioning

confidence: 99%

Differential Responses to Systemic and Local Angiotensin II Infusions in Conscious Postnatal Sheep

Velaphi

2002

Pediatric Research

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“…Samples of umbilical and carotid artery and abdominal aorta were collected from 20 fetal sheep between 85 and 146 d gestation (term 145 d); samples of carotid artery and aorta were also obtained from 6 postnatal (5-23 d) and 3 adult sheep of mixed Western breed. These vessels were studied because we (9,19,29) previously identified differences in VSM maturation and function as well as AT subtype in umbilical and peripheral arteries at term. Animals were killed with i.v.…”

Section: Methodsmentioning

confidence: 99%

“…In pregnant animals, the fetus was rapidly delivered, dried, weighed, and measured to confirm gestational age. A 6-to 8-cm segment of umbilical cord was obtained, and both umbilical arteries were dissected, placed into chilled physiologic based saline, and maintained on ice as previously described (29,32). Residual blood was expressed, and Wharton's jelly and adventitia were removed using blunt and sharp dissection.…”

Section: Methodsmentioning

confidence: 99%

“…SDS homogenates were prepared from 15-to 20-mg samples of frozen denuded samples of umbilical and carotid artery using methods previously reported (29). The homogenate was divided into two aliquots; one was subjected to centrifugation at 10,000 ϫ g for 2 min and the supernatant was removed, providing samples of total and soluble or cellular protein, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…Thus we sought to determine 1) whether ovine AT subtype expression in VSM is developmentally regulated and tissue specific, 2) whether differences exist in AT subtype expression in umbilicoplacental and systemic vasculature during development, and 3) whether subtype regulation differs at a molecular level. We studied the umbilical artery, because it regulates fetal oxygen and nutrient delivery and is more sensitive to Ang II at term than the systemic vasculature (9,29,30), and the carotid artery, because it contributes to cerebral blood flow regulation (31). We also examined aortic VSM as it has been extensively studied in the rat and mouse.…”

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Vessel-Specific Regulation of Angiotensin II Receptor Subtypes During Ovine Development

et al. 2005

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Umbilical and systemic responses to angiotensin II differ in term fetal sheep, and peripheral vascular responses are attenuated or absent before and after birth. These observations may reflect developmental differences in angiotensin II receptor (AT) subtypes in vascular smooth muscle (VSM). Studies of AT subtype ontogeny and regulation are generally limited to the aorta, which may not be extrapolated to other arteries, and neither is completely described during ovine development. We therefore characterized VSM AT subtype expression and regulation throughout an extended period of development in umbilical and carotid artery and aorta from fetal (85-146 d gestation), postnatal (5-23 d), and adult sheep, measuring AT 1 and AT 2 mRNA and protein and performing immunohistochemistry. Parallel increases in umbilical AT 1 mRNA and protein began early in gestation and continued to term, and although AT 2 mRNA was unchanged, protein levels decreased Ͼ90% at term. Fetal carotid AT 1 mRNA was Ͻ40% of adult values and unchanged before birth; however, AT 1 protein rose Ͼ2-fold at term. After birth, AT 1 mRNA increased to 85% of adult values and was associated with another 2-fold rise in protein. In contrast, carotid AT 2 mRNA and protein fell in parallel throughout development and were barely detectable in the newborn and the adult. Immunostaining was consistent with observations in both arteries. A third pattern occurred in aortic VSM. The ontogeny of AT subtype expression and regulation is vessel specific, with changes in umbilical VSM beginning very early in development. Although the mechanisms that regulate mRNA and protein expression are unclear, these changes parallel differences in VSM maturation and function and local blood flow. The renin-angiotensin system (RAS) is expressed early in gestation and considered an important modulator of cardiovascular development, adaptation, and blood pressure control before and after birth (1-4). In fetal and neonatal sheep, hemorrhage and hypovolemia increase circulating angiotensin II (Ang II) (5-7). Although inhibition of Ang II receptors (AT) or converting enzyme accentuates hypovolemic episodes (3,7), their effects on basal arterial pressure are inconsistent (8,9). AT blockade also modifies the baroreflex and reflex control of renal sympathetic nerve activity after birth (10,11). Recent evidence suggests the RAS also contributes to the differentiation, maturation, and/or growth of vascular smooth muscle (VSM) (12-15). Thus, prevailing evidence suggests the RAS contributes to the regulation of vascular function, maturation, and growth during development.The effects of the RAS are mediated primarily by Ang II activation of ATs, which belong to the superfamily of seven transmembrane receptors (12,16,17). They are present in mammalian fetal and adult VSM and demonstrate similar binding characteristics during development and in the adult (18 -20). In fetal sheep, AT binding density and affinity in aorta and placental arteries are unchanged in the last third of gestation and resemble ...

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Functional differences between the arteries perfusing gas exchange and nutritional membranes in the late chicken embryo

et al. 2015

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The chicken extraembryonic arterial system comprises the allantoic arteries, which irrigate the gas exchange organ (the chorioallantoic membrane, CAM) and the yolk sac (YS) artery, which irrigates the nutritional organ (the YS membrane). We compared, using wire myography, the reactivity of allantoic and YS arteries from 19-day chicken embryos (total incubation 21 days). The contractions induced by KCl, the adrenergic agonists norepinephrine (NE, nonselective), phenylephrine (α1), and oxymetazoline (α2), electric field stimulation (EFS), serotonin, U46619 (TP receptor agonist), and endothelin (ET)-1 and the relaxations induced by acetylcholine (ACh), sodium nitroprusside (SNP, NO donor), forskolin (adenylate cyclase activator), and isoproterenol (β-adrenergic agonist) were investigated. Extraembryonic allantoic arteries did not show α-adrenergic-mediated contraction (either elicited by exogenous agonists or EFS) or ACh-induced (endothelium-dependent) relaxation, whereas these responses were present in YS arteries. Interestingly, the intraembryonic segment of the allantoic artery showed EFS- and α-adrenergic-induced contraction and ACh-mediated relaxation. Moreover, glyoxylic acid staining showed the presence of catecholamine-containing nerves in the YS and the intraembryonic allantoic artery, but not in the extraembryonic allantoic artery. Isoproterenol- and forskolin-induced relaxation and ET-1-induced contraction were higher in YS than in allantoic arteries, whereas serotonin- and U46619-induced contraction and SNP-induced relaxation did not significantly differ between the two arteries. In conclusion, our study demonstrates a different pattern of reactivity in the arteries perfusing the gas exchange and the nutritional membranes of the chicken embryo.

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Differential development of umbilical and systemic arteries. II. Contractile proteins

Cited by 24 publications

References 37 publications

Differential Responses to Systemic and Local Angiotensin II Infusions in Conscious Postnatal Sheep

Differential Responses to Systemic and Local Angiotensin II Infusions in Conscious Postnatal Sheep

Vessel-Specific Regulation of Angiotensin II Receptor Subtypes During Ovine Development

Functional differences between the arteries perfusing gas exchange and nutritional membranes in the late chicken embryo

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