Influence of some lipid lowering drugs on the vascular reactivity in experimental animals

The responsiveness of blood vessels to a wide range of vasoactive substances is known to be altered in various forms of hypercholesterolemia, little is so far known about the effect of hypolipidemic drugs on the accompanied vascular reactivity changes. In order to assess the effect of lipid lowering drugs on the vascular reactivity, the present study was designed to investigate the effect of long term treatment with bezafibrate, acipimox, and magnesium pyridoxal 5-phosphate glutamate "MPPG" on isolated rabbit aorta and renal artery ring preparations. It was found that pretreatment of hypercholesterolemic rabbit with hypolipidemic drugs was accompanied by normalization of all deranged reactivity parameters tested. Even in normocholesterolemlic control rabbits, pretreatment with the same hypolipidemic drugs decreased the contractile responses and augmented the relaxant responses

Effect of cooling on contraction of sensitized guinea-pig trachea

The effect of cooling on contractility of ovalbumin sensitized guinea pig trachea was elucidated and the possible mechanisms underlying the effects of cooling on contractility induced by histamine, 5-HT and ovalbumin were investigated. Cooling of temperature from 37C to 25C is associated with significant increase in tracheal contractions to exogenously administered 5-1T, histamine and ovalbumin. Verapamil incubation [10 muM] produced significant depression of the contractile responses at 25C but not at 37C. These results demonstrated that the cooling induced contractile augmentation of the sensitized guinea-pig trachea to ovalbumin is due to 5-HT and histamine. The mechanisms of this augmentation may involve the increased opening of calcium channels in the membranes to allow calcium influx or the mobilization of calcium from intracellular calcium stores