Mesenteric arterial effective flow

Bermet L, Quaedackers J, Gunn A, Rossenrode S, Heineman E. The effect of asphyxia on superior mesenteric artery blood flow in the premature sheep fetus. J Pediatr Surg 2000 35(l) 34-40. 

Mesenteric artery was studied in the B and D KOs (Table 3). The B KO had no change in PE EC50 or maximum in rings, whereas the D KO had a decreased pressor response to PE in an isolated mesenteric bed preparation (3,7). This evidence for the D in mesenteric arteries fits binding data in WT mice (22a). Carotid and tail artery rings from the B KO had no change in PE effects, except that the carotid from the B KO was more sensitive to PE (7). Coronary arteries were studied in the D and AB KOs by examining coronary flow or pressure in the isolated perfused heart (16,18). Both studies pointed to a role of the D in coronary... 

The intestine is isolated and perfused via the mesenteric artery with oxygenated perfusate, preferably, heparinized blood at 37°C and at a physiological pressure and blood flow. Venous blood from the portal vein is either collected first pass or returned to the reservoir for reoxygenation and recirculation. The effect of bile on absorption from the gut can be assessed by the infusion of bile via an indwelling cannula that is inserted into the bile duct in the direction of the gut. 

Smooth Muscle. All known calcium inhibitory compounds decrease smooth muscle tone in both the coronary and peripheral circulations (11 , 114, 115, 140, 145-147). Comparative studies using dogs suggest that this effect varies in intensity but surpasses negative inotropic activity (114, 145). Nifedipine, verapamil and perhexiline exhibit their most pronounced vasodilator effects upon femoral arterial blood flow followed by coronary, renal, and mesenteric beds (44, 47,... 

We next examined whether a higher output of NO might be necessary in order for a modulatory effect of NO on NE release to take place. For this, we doubled the mesenteric artery flow so as to elicit an increase in perfusion pressure, which is known to cause intravascular shear and, thus, increased NO production (Busse et al., 1985). As shown in Fig. 3, despite a threefold increase in perfusion pressure (cf. Figs. lA and 3A), SNP (1 xM) and NMA (300 /xM) still decreased and enhanced this pressure, respectively, but without affecting NE release. Thus, even when its output is increased by shear stress, NO appears not to down-regulate NE release. With SNP no increase in NE release occurred, as opposed to the increase reported in Fig. 2B, because the a2-adrenoceptor-mediated negative-feedback loop was... 

The cardiovascular action of SM to lower systemic blood pressure in the rats has been demonstrated. Langendorff cardiac preparation in guinea pig and four types of vasculature in dog, including coronary, renal, femorid, and mesenteric arteries are performed. SM induces dose-related hypotension without changing heart rate. Atropine, propranolol, and chlorpheniramine plus cimetidine antagonize the hypotensive effect. In the isolated whole-heart preparation, SM injection increases coronary blood flow and causes a positive inotropic action. SM relaxes all arteries at low concentration and contracts all, but the coronary artery, at high concentration (7P). 

Brandt, L., Andersson, K. E., Edvinsson, L., Ljunggren, B., 1981 b Effects of extracellular calcium and of calcium antagonists on the contractile responses of isolated human pial and mesenteric arteries. J. Cereb. Blood Flow Metab. 1, -339-347. 

Age-dependent, receptor-mediated drug effects have been observed with dopamine. The effect of dopamine on blood flow (estimated by measuring the pulsatility index by ultrasonography) was assessed in the right renal, superior mesenteric, and middle cerebral arteries in sick premature infants (52). Renal blood flow increased during the dopamine infusion, but mesenteric and cerebral blood flow were not altered. In adults, dopamine does increase blood flow to the intestine, indicating that the lack of response in preterm neonates is related to the immaturity of the mesenteric vascular bed. 

LTC and LTD cause hypotension from a decrease in intravascular volume and also from decreased cardiac contractility secondary to a marked LT-induced reduction in coronary blood flow. Although LTC and LTD have little effect on most large arteries or veins, coronary arteries and distal segments of the pulmonary artery are contracted by nanomolar concentrations of these agents. The renal vasculature is resistant to this constrictor action, but the mesenteric vasculature is not. 

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