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We investigated the folding of the 70 kDa human cytosolic inducible protein (Hsp70) in vitro using high hydrostatic pressure as a denaturing agent. We followed the structural changes in Hsp70 induced by high hydrostatic pressure using tryptophan fluorescence, molecular dynamics, circular dichroism, high-performance liquid chromatography gel filtration, dynamic light scattering, ATPase activity, and chaperone activity. Although monomeric, Hsp70 is very sensitive to hydrostatic pressure; after pressure had been removed, the protein did not return to its native sate but instead formed oligomeric species that lost chaperone activity but retained ATPase activity.

In this work, we evaluated the effects of allopurinol (ALO), an inhibitor of xanthine oxidase (XO), on hepatic lesions caused by ischemia/reperfusion (I/R) in the rabbit liver. Rabbits were pretreated with ALO (10 mg/kg IV) or saline solution 0.9% before the hepatic I/R procedure. The effects of ALO on hepatic injury were evaluated before and after I/R. A standard, warm hepatic I/R procedure caused profound acute liver injury, as indicated by elevated serum aspartate aminotransferase, alanine aminotransferase, and lactic dehydrogenase levels, as well as a high apoptotic cell count. All of these changes were reversed by the administration of ALO before the hepatic I/R procedure. In conclusion, ALO exerted protective effects on hepatic I/R lesions. This protective effect of ALO was probably associated with blocking the generation of superoxide anions during the hepatic I/R procedure by inhibiting XO activity.

We evaluated the effects of a substrate in the biosynthesis of nitric oxide (NO)-l-arginine (LARG)-on hepatic lesions caused by ischemia/reperfusion (I/R) injury in rabbit livers. Rabbits were pretreated with LARG (150 mg/kg IV) or saline solution 0.9% (SS) before the hepatic I/R procedure. The effects of LARG on hepatic injury were evaluated before and after I/R. The warm hepatic I/R procedure produced profound acute liver injury, as indicated by elevated values of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactic dehydrogenase (LDH), as well as a high apoptotic cell count. All changes were attenuated by treatment with LARG before the hepatic I/R procedure. These results suggested that LARG produced protective effects on hepatic I/R lesions. This protective effect of LARG was probably associated with blocking generation of superoxide anions during the hepatic I/R procedure.

To study whether treatment with the beta-blocker atenolol (AT) attenuates intestinal dysfunction caused by ischemia (I) and reperfusion (R), rabbits were treated with AT (1 mg.kg(-1), introvenously) or saline solution (SS) prior to I (60 minutes), which was produced by occlusion of the superior mesenteric artery, and/or R (120 minutes). After I or I/R, 2-cm jejunal segments were mounted in an organ bath to study neurogenic contractions stimulated by electrical pulses or KCl using a digital recording system. Thin jejunal slices were stained hematoxylin and eosin for analysis by optical microscopy. Compared to the sham group, the jejunal contractions were similar in the I + AT and the I/R + AT groups, but reduced in the I + SS and the I/R + SS groups. The jejunal enteric nerves were damaged in the I + SS and the I/R + SS groups, but not in the I + AT and the I/R + AT. These results suggest that AT may attenuate intestinal dysfunction caused by I and I/R.

To study whether treatment with L-nitro-arginine methyl ester (L-NAME), an inhibitor of nitric oxide biosynthesis, attenuates intestinal dysfunction caused by ischemia (I) and/or reperfusion (R), rabbits were treated with L-NAME (15 mgxkg(-1), intervenously) or saline olution (SS) prior to I (60 minutes) induced by occlusion of superior mesenteric artery and/or R (120 minutes). After I or I/R, isolated jejunal segments (2 cm) were mounted in an organ bath to study nerve-mediated contractions stimulated by electrical pulses or KCI using a digital recording system. Thin jejunal slices were stained (hematoxylin and eosin) for analysis by optical microscopy. Compared with a sham group, the jejunal contractions were similar in the I/R + L-NAME, but reduced in I + SS, I/R + SS, and I + L-NAME groups. The jejunal enteric nerves were damaged in the I + SS, I/R + SS, and I + L-NAME cohorts, but not among the I/R + L-NAME cohort. These results suggested that L-NAME attenuated intestinal dysfunction caused by R but not by I.

To study whether treatment with 5'-adenosine triphosphate (ATP), an agonist of P2 purine receptors, attenuated intestinal dysfunction caused by ischemia (I) and/or reperfusion (R), rabbits were treated with ATP (15 mgxkg(-1), intravenously) or saline solution (SS) 60 minutes before I by occlusion of the superior mesenteric artery and/or R (120 minutes). After I or I/R isolated 2-cm jejunal segments were mounted in an organ bath to study nerve-mediated contractions stimulated by electrical pulses or KCl using a digital recording system. Thin jejunal slices were stained (hematoxylin and eosin) for optical microscopy. Compared to a sham group, the jejunal contractions were similar to sham hosts among I + ATP, but reduced in I + SS, I/R + SS, and I/R + ATP groups. The jejunal-enteric nerves were damaged in I + SS, I/R + SS, and I/R + ATP, but not the I + ATP group. These results suggested that ATP attenuated intestinal dysfunction produced by I, but not that caused by R.

In this work, we evaluate the effects of adenosine 5' triphosphate (ATP) on hepatic lesions caused by ischemia/reperfusion (I/R) in liver rabbit. Rabbits were pretreated with ATP (15 mg/kg IV) or saline solution 0.9% (SS), before the hepatic I/R procedure. We evaluated the effects of ATP on hepatic injury before and after I/R. The warm hepatic I/R procedure caused profound acute liver injury, as indicated by elevated serum aspartate aminotransferase, alanine aminotransferase, and lactic dehydrogenase levels, as well as a high apoptotic cell count. All these changes were attenuate by ATP treatment before the hepatic I/R procedure. These results suggested that ATP exerted protective effects on hepatic I/R lesions in the rabbit. This ATP effect may be related to improved energy metabolism during reperfusion in ischemic livers protecting against functional damage of cellular and subcellular membranes during lipid peroxidation.

Because the role of heparin (HEP) in hepatic ischemia/reperfusion (I/R) injury is still not fully understood, we investigated the effects of treatment with HEP on hepatic I/R injury in rabbits. For I/R procedures, the portal vein and hepatic artery were occluded by a metallic clamp to promote ischemia. The clamp was removed after 30 minutes to allow reperfusion. Rabbits undergoing the I/R procedure were treated with HEP (100 U/kg) or saline solution 0.9% (SS). When compared with levels before I/R, the serum aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase, levels were increased by the hepatic I/R procedure, among rabbits treated with SS or HEP. However, the increase in these enzymes was lower among rabbits treated with HEP. Histologic analysis of hepatic tissue of rabbits undergoing I/R and treated with SS showed marked lesions in the central lobule with significant inflammatory infiltration. In contrast, a significant reduction in lesions caused by I/R was observed in the livers of rabbits treated with HEP. After starting reperfusion, we visualized apoptotic cells with nuclear staining among rabbits submitted to I/R and treated with SS, but not those treated with HEP. These results suggested that HEP was able to attenuate hepatic lesions caused by I/R in the livers of rabbits.