HISTOLOGICAL AND HISTOCHEMICAL CHANGES IN CANINE MYOCARDIAL ISCHEMIA
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
Description
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.