Contraction In Mesenteric Veins Research Articles

Diabetes-Induced Enhancement of Prostanoid-Stimulated Contraction in Mesenteric Veins of Mice

We investigated the influence of the diabetic state on the contractile response of longitudinal segments of isolated mesenteric vein to prostanoids and leukotriene (LT), and the contribution of the vascular endothelium to modulation of the contractile response was determined. The normal mesenteric vein and de-endothelialized veins of normal (ddY), diabetic KK-CAy and streptozotocin ddY mice (150 mg/kg, i.v., 6 weeks) were used. In the diabetic state, the contractions produced by noradrendline (60 μM), high K+ solution (143.4 mM), and the thromboxane A2 analogue U-46619 (29 nM–29 mM) were not affected, and LTD4 (0.1 nM-1 μM)-induced contraction was suppressed. Contractions induced by prostaglandin (PG) E2 (0.2 μM-2 mM), PGF2α (0.3 μM-0.3 mM) and the prostacyclin derivatives PGI2-Na (10–100 μM) and TRK-100 (0.2 μM–2 mM) were significantly enhanced in the presence of an intact vascular endothelium, but not in de-endothelialized segments. The increase in PGF2α (0.28 mM) contractions was dependent on age (correlation coefficient r=0.36, significant difference, P< 0.05) and blood glucose (r=0.88, significant difference, P<0.01), but was independent of obesity. The contractile response to PGD2 (0.3–0.9 mM) was enhanced in both intact and de-endothelialized segments. These results indicate that the diabetic state affects prostanoid responses in an endothelium-dependent manner, except for the PGD2 response, which is independent of the endothelium.

Regional differences in the response of isolated human vessels to vasoactive substances

1. 1. Crural, mesenteric and pulmonary vessels obtained during surgery were studied. Isometric tension was recorded and contractions were induced by potassium 127 mM (K), noradrenaline 18 μM (NA), prostaglandin F 2α 2.9 μM ( F 2α), ergotamine 3.8 μM (Erg) or digoxin 1.0 μM (Dig). 2. 2. Spontaneous myogenic activity was only observed in pulmonary veins. F 2α induced spontaneous activity in mesenteric arteries. 3. 3. In all types of vessels, except in mesenteric arteries, the response to K + had a greater amplitude than contractions developed by NA. Erg induced a slowly developing contraction in mesenteric veins but no contraction in mesenteric arteries. Dig induced a long-lasting monophasic response in arteries and a biphasic response in the veins. 4. 4. After immersion for 30 min in a Ca-free medium the amplitudes to both NA and K + were significantly reduced. The veins were more susceptible to the effects of Ca-deprivation than the arteries.