Differences in the regional distribution and response to ischaemia of adenosine-regulating enzymes in the heart

Abstract

The activities of the adenosine-generating enzyme 5'-nucleotidase and the adenosine-degrading enzyme adenosine deaminase were determined for four regions of rat hearts prior to and following 10-60 min of ischaemia. Whereas adenosine deaminase was uniformly active throughout the heart, 5'-nucleotidase was twice as active in atrial than in ventricular myocardium, and more active in the right than in the left ventricles in normoxic tissues. In isolated heart preparations normoxic perfusion decreased adenosine deaminase and increased 5'-nucleotidase activity compared to levels in vivo. Global ischaemia for 10 min elevated adenosine deaminase activity but had no effect on 5'-nucleotidase activity. However, 30 min of ischaemia decreased 5'-nucleotidase activity by 50% in all regions of the heart. These changed levels were not altered by 10 min of reperfusion. The fall in 5'-nucleotidase activity with ischaemia occurred only in the 90% of this enzyme which is membrane-bound. The reasons for the marked differences in distribution and responses to ischaemia of these two enzymes have yet to be elucidated but metabolic inhibitors seem unlikely to be involved.

Effects of caffeic acid phenethyl ester and alpha‐tocopherol on reperfusion injury in rat brain

“…All procedures were performed at þ 4 C. The determinations listed below were made on the samples according to the cited references at the Biochemistry Laboratory of Turgut Ozal Medical Center using products by Sigma. MDA 19 and NO (nitrate was measured as an index of NO production) 20 levels were determined in the homogenate, ADA, 21 XO, 22 CAT, 23 GSH-Px 24 activity in the supernatant and SOD activity in the extracted samples 25 according to the methods described elsewhere. Protein measurements were made at all stages by the method described by Lowry.…”

Caffeic acid phenethyl ester changes the indices of oxidative stress in serum of rats with renal ischaemia–reperfusion injury

“…15 One unit of activity was de®ned as 1 mmol of uric acid formed per minute at 37 C, pH 7.5, and expressed in IU ml À 1 . ADA activity was determined by a method described elsewhere 16 and enzyme activity was expressed as Ul À 1 . Since nitrite (NO 2 À ) and nitrate (NO 3 À ) levels can be used to estimate NO production, we measured the concentrations of these stable NO oxidative metabolites for determining the NO levels.…”

The regional distribution of adenosine-regulating enzymes in the left and right ventricle walls of control and hypertrophic heart

“…In addition, Deusscn et al (5) have reported that S-adenosylhomocysteine hydrolase may have an important role in the regulation of the free cytosolic adenosine concentration. Recently, Choong and Humprey (6) have reported that 5'N and ADA enzyme activities exhibit regional differences in their distribution in the rat heart. In previous work we showed that these two enzyme activities are not uniformly distributed across the rat left ventricle wall (7) and that the profiles of their distribution across the heart wall are strongly influenced by growth and aging (8).…”