We have tested the hypothesis that cerebral nitric oxide (NO) production is involved in hyperbaric O(2) (HBO(2)) neurotoxicity. Regional cerebral blood flow (rCBF) and electroencephalogram (EEG) were measured in anesthetized rats during O(2) exposure to 1, 3, 4, and 5 ATA with or without administration of the NO synthase inhibitor (N(omega)-nitro-L-arginine methyl ester), L-arginine, NO donors,...

1. The role of nitric oxide as mediator of the vascular alterations present in different models of experimental liver cirrhosis is controversial. In the present study, we evaluated the role of nitric oxide and that of the endothelium in the response to phenylephrine and acetylcholine of isolated aortic rings from chronic bile duct-ligated (29 days) rats and their corresponding controls. Experim...

Atropine has been used to block cholinergic neurotransmission in basic research. Large doses of atropine cause vasodilation of the blood vessels in the skin. This effect is apparently unconnected with the antimuscarinic activity of atropine and seems to be due to a direct action on the blood vessels. It has been suggested that atropine blocks muscarinic receptors at low doses and it induces th...

In experimental animals, systemic administration of nitric oxide synthase (NOS) inhibitors causes large increases in blood pressure that are in part sympathetically mediated. The aim of this study was to determine the extent to which these conclusions can be extrapolated to humans. In healthy normotensive humans, we measured blood pressure in response to two NOS inhibitors, NG-monomethyl-L-argi...

A protease was purified from Bacteroides gingivalis ATCC 33277 culture fluid by sequential procedures including ammonium sulfate precipitation, ion-exchange chromatography, and isoelectric focusing. The enzyme was active against benzoyl-L-arginine-p-nitroanilide, carbobenzoxy-L-phenylalanyl-L-valyl-L-arginine-p-nitroanilide azoalbumin, azocasein, azocoll, and p-tosyl-L-arginine methyl ester. Th...

Objective(s):The aim of this study was to investigate the effects of nutritional saffron (Crocus sativus L.) stigma hydroalcoholic extract on blood pressure (BP) and histology of the aorta in normotensive and hypertensive rats. Materials and Methods:   Saffron (200 mg/kg/day) was given orally for 5 weeks to normotensive and hypertensive rats. Hypertension was induced by NG-nitro-L-arginine meth...

Trypsin catalyses the hydrolysis of suitable derivatives of basic amino acids including peptides, amides and esters. Esters are the most sensitive substrates, and it was decided to use them in the present study, which had as one of its aims the elucidation of the relationship between the length of the side chain and susceptibility to hydrolysis by trypsin. Previous investigations had shown that...