HISTOLOGICAL AND HISTOCHEMICAL CHANGES IN CANINE MYOCARDIAL ISCHEMIA

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Date
1988-01
Authors
IBRAHIM, NAJUME DOGUWAR-GIGINYA
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Abstract
A total of 1+2 healthy dogs with no indication of disease were used for the experiment, out of them 9 died during surgery The remaining 33 dogs were divided into 2 experimental groups. In the 1st group of experiment the hearts of 11 dogs were infarcted by ligating LAP after thoracotomy for 1.0 hour and the ligature was removed to reperfuse the heart for 1 day; 4 dogs were control with shams incision. In the 2nd experimental group the hearts of 16 dogs were infarcted for 1.0 hour by ligating LAD after thoracotomy and the ligature was removed to reperfuse the heart for 7 days, while 2 dogs were used as control and had shams incision. After completion of reperfusion period, dogs were euthanized and necropsy was performed on each. Grossly, the heart was rounded and flabby with scattered petecheal hemorrhages in case of reperfused hearts while control hearts were normal. Five samples were taken from the left ventricle of each reperfused and of control hearts • Heart tissue was sectioned with minotome cryostat to obtain 5 - 6 micron thick frozen sections. Sections were histochemically stained for MPO, and counter stained with hematoxylin and eosion. four different fields per slide were examined under light microscope and the heterogenous myocyte injury, number of leukocytes and extracellular granules were counted for each field and the data were statistically analysed. The myocyte injury was evaluated in tissue sections and scored as 0 to 3 depending upon the structural alterations in the myrocytes, score 0 as no alteration, score 1 as mild injury, score 2 as moderate and score 3 as most severe myocyte injury. In dogs maintained for 1 day the score 1 myocyte injury was most prevalent and the least was with score 3, while in control dogs score 0 was most common. In dogs maintained for 7 days score 2 myocyte injury was most prevalent, while the least was score 0. In the control dogs there was no myocyte injury. There exists close relationship between heterogenous myocyte injury and the number of infiltrated leukocytes around the injured myocytes with corresponding increased released extracellular granules into the areas with heterogenous myocyte injury. Finally, it is concluded that there is close relationship between the number of leukocytes and extracellular granules aggregation around myocytes and the intensity of myooytes injury. Leukocytes and extracellular granules release H202 which is a substrate for MPO. The presence of H2O2 was demonstrated by using MPO specific histochemical stain and it appears that this free radical is responsible for myocyte reperfusion injury. The implications of this investigation will be helpful for developing new drugs capable of depleting leukocytes and their extracellular granules in treating and preventing cardiac reperfusion injury. It can be used for diagnosis of death due to cardiac reperfusion injury by demonstration of MPO histochemically in frozen heart sections as MPO can not be demonstrated using other convensional staining methods. To understand the role of leukocytic H2O2 in the pathogenesis of reperfusion injury in the heart, which may be similar to reperfusion injury of kidney and intestine
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A Thesis submitted to the Postgraduate School, Ahmadu Bello University, in Partial fulfillment of the requirements for the degree of Master of Science (M.Sc). Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Ahmadu Bello University, Zaria. JANUARY, 1988
Keywords
HISTOLOGICAL,, HISTOCHEMICAL,, CHANGES,, MYOCARDIAL,, ISCHEMIA.
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