The effects of Vaccinium myrtillus anthocyanosides (VMA) on ischaemia reperfusion injury were investigated in the hamster cheek pouch microcirculation. Ischaemia was induced by clamping the cheek pouch for 30 min followed by 30 min of reperfusion. The microvasculature was visualized by a fluorescence technique. VMA [10 mg (100 g body weight)-1] were orally administered for 2 and 4 weeks. The number of adhering leukocytes to venular vessel walls, the perfused capillary length, the increase in permeability, the arteriolar diameter changes were determined. Ischaemia and reperfusion were associated with increased number of leukocytes sticking to venules, decreased number of perfused capillaries, and increased permeability. VMA decreased the number of leukocytes sticking to the venular wall and preserved the capillary perfusion; the increase in permeability was significantly reduced after reperfusion. VMA saved the arteriolar tone and induced the appearance of rhythmic diameter changes of arterioles. These results demonstrate the ability of Vaccinium myrtillus anthocyanosides to reduce microvascular impairments due to ischaemia reperfusion injury, with preservation of endothelium, attenuation of leukocyte adhesion and improvement of capillary perfusion.

Animals↗

PubMedDate not supplied

Insulin-induced arteriolar dilation after tyrosine kinase and nitric oxide synthase inhibition in hamster cheek pouch microcirculation.

We investigated the effects of tyrosine kinase (TK) and nitric oxide synthase (NOS) inhibition on insulin-induced dilation of arterioles. We determined the arteriolar diameter, red blood cell velocity (VRBC) and blood flow changes in hamster cheek pouch microcirculation as affected by insulin in presence of TK and NOS inhibitors, genistein, piceatannol and NG-monomethyl-L-arginine (L-NMMA). Microvessels were visualized by a fluorescent microscopy technique. Arteriolar diameter and VRBC were measured after topical application of insulin and genistein or piceatannol or L-NMMA. Insulin (10 microU/ml) induced diameter and VRBC increase in A3 and A2 arterioles by 30 +/- 5 and 123 +/- 4%, 16 +/- 4 and 102 +/- 3%, as percent of baseline values, respectively. After genistein or piceatannol prior to insulin A3 and A2 arterioles dilated by 10 +/- 4, 5 +/- 2% and 9 +/- 4, 2 +/- 1%, respectively. After L-NMMA prior to insulin A2 and A3, arteriole diameters increased by 12 +/- 3 and 7 +/- 2%, respectively. VRBC increased significantly in all the cases. TK and NOS inhibitors applied together abolished insulin-induced dilation with a reduction in VRBC and blood flow. In conclusion, full insulin-induced dilation of hamster cheek pouch arterioles requires TK signaling pathways. Furthermore, activation of insulin receptors, as well as other TK receptors, appears to be required for vasomotor tone regulation.

Animals↗