Reflex vascular responses in kidney, ileum, and forelimb to carotid body stimulation

Parker, PE; Jm, Dabney; Jb, Scott; Fj, Haddy

doi:10.1152/ajplegacy.1975.228.1.46

Cited by 21 publications

(9 citation statements)

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“…The increases in CNS and diaphragm flows were qualitatively similar to those in our fetuses and Matalon's adults (21). These increases in flow were accompanied by significant decreases in splenic and stomach blood flows, as well as consistent (seven of seven animals) but not statistically significant decreases in small bowel and renal blood flows, perhaps due to the predominance of vasoconstrictive effects of CO2mediated by central vasomotor centers (15) and/or peripheral chemoreceptors (27). These decreases were not observed in the fetus, which could be due to immaturity of the fetal autonomic nervous system (5,14,34).…”

Section: Discussionsupporting

confidence: 77%

“…Individual vesselsmay dilate because of the local effects of CO2• This has been shown experimentally in a variety of vascular beds including cerebral (20), mesenteric (7), coronary (9), renal (13), and limb (13,29). On the other hand, hypercapnia provokes peripheral vasoconstriction via an effect both on the central nervous system (15) and peripheral chemoreceptors (27). Elevations in Paco, also increase respiration and stimulate the pulmonary stretch receptors which induce skin, muscle, renal, and splanchnic vasodilation (12,32).…”

Section: Discussionmentioning

confidence: 99%

“…Disturbances in the transfer of nutrients from mother to fetus, reflecting altered placental function, may be of importance for the decreased somatic growth rate (17,18). Besides, the magnitude of the placental blood flow determines the amount of nutrients available for transfer to the fetus (27). Therefore , placental blood flow may be relevant to fetal growth retardation (28).…”

Section: Diabetes In Pregnancy: Decreased Placental Blood Flow and DImentioning

confidence: 99%

“…Although a number of estimations of placental blood flow in rodents have been reported (I , 2,5,7,15,16,27,29,34), no studies of placental blood flow in diabetic rat pregnancy seem to have been published. There are, however, reports of altered placental morphology (26) and indirect evidences of changed vascular function in diabetic rat placenta (4) as well as decreased transfer of aminoisobutyric acid to fetuses ofdiabetic guinea pigs (30).…”

Section: Diabetes In Pregnancy: Decreased Placental Blood Flow and DImentioning

confidence: 99%

“…Nonlinearity characterized some of the responses of regional blood flows as well. These variable responses are not surprising when one considers that regional blood flow in hypercapnia depends upon complex interactions ofa number of factors including local vasodilation by CO 2 (7,9,13,20,29), vasodilation mediated by the pulmonary inflation reflex (12,32), vasoconstriction induced by a central effect of CO2 on vasomotor centers (15), and vasoconstriction induced by effectson peripheral chemoreceptors (27). Given the complicated nature of these interactions, one might anticipate considerable differences in the response to respiratory acidosis before and after birth.…”

mentioning

confidence: 99%

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Distribution of Cardiac Output in Fetal and Neonatal Lambs with Acute Respiratory Acidosis

1984

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SummaryThe effects of changes in PaC02on the circulation are complex, involving local vasodilation, vasodilation mediated by the pulmonary inflation reflex, and vasoconstriction due to effects on central vasomotor centers and peripheral chemoreceptors. One might anticipate that some or all of these inight differ between the fetus in uteroand the newborn. Distribution of cardiac output was measured in unanesthetized fetal (n =6) and newborn (n = 7) sheep, using the radioactive microsphere technique. Paco, rose from 44 to 70 (fetus) and 38 to 60 torr (newborn) with the addition of CO2 to room air. In the fetus, there were significant increases in central nervous system (CNS), diaphragm, and lung blood flows. No organ showed a significant decrease in flow. Local vasodilation by CO 2 was the likely cause of the increased flow to CNS. The large increase in pulmonary blood flow was most likely due to the associated rise in fetal Pao, (23 to 28 torr) that accompanied respiratory acidosis and the presence of fetal breathing movements. The rise in diaphragmatic blood flow was -likely the result of fetal breathing. In the newborn, CNS and diaphragm flows rose, but unlike the fetus, spleen and stomach flows decreased. These decreased flows in the hypercapnic newborn may have been due to stimulation of either central vasomotor centers or peripheral chemoreceptors.Abbreviations CNS, central nervous system . DAo, descending aorta DA, ductus arteriosus I, aortic isthmus PA, pulmonary artery (2, blood flow C, radioactive countsStudies of the redistribution of cardiac output induced by hypoxia in fetal and adult animals (I, 4, 10) have shown that cardiac, cerebral, and adrenal oxygen delivery is preserved at the expense of other organs. Redistribution is accomplished by a local effect of hypoxia which dilates cerebral and coronary vessels, while the chemoreceptor reflex produces vasoconstriction in skeletal muscle and splanchnic beds (16).The circulatory effects of changes in Paco-, on the other hand, have not been as carefully studied . In particular, there are no data comparing effects before and after birth. The response of cardiac output and its regional distribution to changes in Paco, has been looked at in an acute fetal preparation but blood flow was measured only in major arteries (3). Only recently has the regional blood flow response been described in quantitative detail in a conscious adult animal (21). These studies done on adult sheep have shown that the effect of CO2 on the circulation is nonlinear. Cardiac output is unchanged as Paco; increases from 36 to 58 mm Hg; however, a 35% increase occurs as Paco, is further increased to 75 mm Hg. Nonlinearity characterized some of the responses of regional blood flows as well. These variable responses are not surprising when one considers that regional blood flow in hypercapnia depends upon complex interactions ofa number of factors including local vasodilation by CO 2 (7,9, 13, 20, 29), vasodilation mediated by the pulmonary inflation reflex (12, 32), vasoconstriction ind...

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