The effects of cooling (to 28 degrees C) and warming (to 41 degrees C) on the vasoconstrictions induced by 5-hydroxytryptamine (5-HT) and acetylcholine (ACh) and the role of nitric oxide in these effects were analyzed in human umbilical artery and vein. 5-HT (10(-9)-10(-4) M) and ACh (10(-9)-10(-4) M) induced concentration-dependent contractions at 37, 28 and 41 degrees C. During cooling, the sensitivity, but not the maximal response, of 5-HT and ACh was significantly higher than at 37 degrees C; and during warming, again the sensitivity, but not the maximal response, of both contractile agents was significantly lower than at 37 degrees C. Neither cooling to 28 degrees C nor warming to 41 degrees C, after treatment with N(G)-nitro-L-arginine methyl esther (L-NAME, 10(-4) M), modify the effect of temperature in both vessels. These results suggest that cooling- and warming-induced responses in human umbilical artery and vein are independent of nitric oxide.

In the present study, the eŠects of cooling (to 28°C) on the vasodilatation induced by diazoxide (10 -9 -3×10 -4 M), isoproterenol (10 -9 -3×10 -4 M) and magnesium sulphate (0.1 30 mM) on serotonin-pre-contracted human umbilical artery and the role of nitric oxide in these eŠects were analyzed. Diazoxide, isoproterenol and magnesium produced concentration-dependent relaxation of human umbilical artery precontracted with serotonin (10 -6 M). During cooling, the pIC 50 values and maximal responses to these agents were signiˆcantly lower than at 37°C. Cooling to 28°C in the presence of N G -nitro-L-arginine methyl ester (L-NAME, 10 -4 M) did not modify the eŠects of temperature on diazoxide, isoproterenol and magnesium-induced relaxations. These results suggest that cooling-induced changes of diazoxide, isoproterenol, and magnesium sulphate in human umbilical artery are independent of nitric oxide.

Objective: At present, very little is known about the effects of donepezil on vascular reactivity. The aim of the present study was to evaluate the responses of rat urinary bladder to donepezil (10-10-3x10-4 M) and the role of Spirulina supplementation in these effects. Material and methods: Animals were divided into the two groups of six animals in each group. The fi rst group received only distilled water daily as vehicle for six weeks and served as the control. The second group received Spirulina 750 mg kg-1 orally, daily for six weeks and served as the spirulina group. Preparations of rat urinary bladder were used from both groups. Results: Donepezil produced concentration dependent relaxation of rat urinary bladder preparations pre-contracted with KCl. The pIC 50 value, but not the maximal response of donepezil, was signifi cantly lower (p<0.05) in the Spirulina supplemented group. Conclusions: These results demonstrated for the fi rst time that spirulina treatment can affect urinary bladder activity (Fig. 1, Ref. 20).