Disorders on cardiovascular parameters in rats and in human blood cells caused by Lachesis acrochorda snake venom.

In Colombia, Lachesis acrochorda causes 2-3% of all snake envenomations. The accidents promote a high mortality rate (90%) due to blood and cardiovascular complications. Here, the effects of the snake venom of L. acrochorda (SVLa) were analyzed on human blood cells and on cardiovascular parameters of rats. SVLa induced blood coagulation, as measured by the prothrombin time test, but did not reduce the cell viability of neutrophils and platelets evaluated by the 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyl tetrazolium bromide (MTT) reduction assay and by the lactate dehydrogenase (LDH) enzyme assay. In fact, SVLa increased the absorbance in tests made with platelets subjected to the MTT assay. SVLa induced platelet aggregation whose magnitude was comparable to that of the positive control adenosine diphosphate (ADP), and occurred earlier with increasing SVLa concentration. Acetylsalicylic acid (ASA, a cyclooxygenase inhibitor) or clopidogrel (an ADP receptor blocker) inhibited the aggregating effect of SVLa. Inhibition of SVLa-elicited platelet aggregation also resulted from the treatment with disodium ethylenediaminetetraacetate (Na2-EDTA; metalloproteinase inhibitor) and with 4-(2-aminoethyl) benzenesulfonyl fluoride hydrochloride (AEBSF, serine protease inhibitor). In isolated right atrium of rats, SVLa increased slightly, but significantly, the magnitude of the spontaneous contractions and, in isolated rat aorta, SVLa relaxed KCl- or phenylephrine-induced contractions. In vivo, SVLa induced hypotension and bradycardia in rats, with detection of hemorrhage in pulmonary and renal tissues. Altogether, under experimental conditions, SVLa induced blood coagulation, platelet aggregation, hypotension and bradycardia. Part of the effects presented here may be explained by the presence of snake venom metalloproteinases (SVMPs) and snake venom serine proteases (SVSPs), constituents of SVLa.

The Preventive Effect on Ethanol-Induced Gastric Lesions of the Medicinal Plant Plumeria rubra: Involvement of the Latex Proteins in the NO/cGMP/K ATP Signaling Pathway.

Plumeria rubra (Apocynaceae) is frequently used in folk medicine for the treatment of gastrointestinal disorders, hepatitis, and tracheitis, among other infirmities. The aim of this study was to investigate the gastroprotective potential of a protein fraction isolated from the latex of Plumeria rubra (PrLP) against ethanol-induced gastric lesions and describe the underlying mechanisms. In a dose-dependent manner, the pretreatment with PrLP prevented ethanol-induced gastric lesions in mice after single intravenous administration. The gastroprotective mechanism of PrLP was associated with the involvement of prostaglandins and balance of oxidant/antioxidant factors. Secondarily, the NO/cGMP/KATP pathway and activation of capsaicin-sensitive primary afferents were also demonstrated as part of the mechanism. This study shows that proteins extracted from the latex of P. rubra prevent gastric lesions induced in experimental animals. Also, the results support the use of the plant in folk medicine.