Effect of ischemia of the rabbit bladder on Ca-Mg-activated ATP-ase activity.
This investigation is concerned with the effect of ischemia on the activity of Ca-Mg-stimulated ATP-ase in rabbit bladder tissue. White New Zealand male rabbits were used for the experiments. Ischemia was produced by clamping of the vesical arteries. After 1 and 2 hours the clamps were removed, and the animals were sacrificed 2 days later. The bladders were removed, and the muscle and mucosal parts of the bladders were separated. In some experiments with 2-hour ischemia the animals were allowed to recover for 7 days. Homogenates were made of the muscle and mucosal tissue and separated by differential centrifugation into three parts: 1) an initial particulate fraction obtained by low-speed centrifugation; 2) a supernate fraction free of mitochondria; and 3) a mitochondrial-rich fraction. ATP-ase activity was determined in the different fractions in the presence of magnesium or calcium as the activating ion, and the results were expressed as nmols/mg protein/minute. The following results were obtained: with the supernates, ischemia was found to produce a marked inhibition of enzyme activity that was large and significant in muscle tissue after 1 hour and in mucosal tissue after 2 hours. Seven days after termination of 1 hour of ischemia, the ATP-ase activity of the muscle fraction had been partially restored towards normal. Activity of ATP-ase when measured in the particulate fraction was less sensitive to the effect of ischemia; a significant diminution of enzyme activity in preparations from muscle was seen only after 2 hours of ischemia, and no inhibition was observed with mucosal tissue. ATP-ase of muscle mitochondria was severely inhibited by ischemia, and the effect of 1 hour of ischemia was not reversed 7 days after the insult. Mitochondria from mucosal tissue were affected to only a small extent by ischemia. In all cases, results were similar whether magnesium or calcium was used for activation of the enzyme.
Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, USA.
B
B
Soyupak
A J
AJ
Wein
R M
RM
Levin
N
N
Haugaard
D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism*; D002498:Centrifugation; D007511:Ischemia / Q000201:enzymology*; D008297:Male; D008931:Mitochondria, Muscle / Q000201:enzymology; D009092:Mucous Membrane / Q000201:enzymology; D011817:Rabbits; D013997:Time Factors; D001743:Urinary Bladder / Q000098:blood supply* / Q000201:enzymology
D017301:Ca(2+) Mg(2+)-ATPase