The characterization of mitochondria isolated from rat myocardium damaged by isoprenaline

33

CRITICAL FLOW: A PARAMETER TO OBSERVE THE EVOLUTION OF INFARCT SIZE OVER 24 HRS IN A CLOSED CHEST CANINE MODEL. M. Gottwik, P. Zimmer, B. Winkler, Max-Planck-Institute, Bad Nauheim, West Germany. W. Schaper, If a threshold flow value could be determined that is able to prevent myocardial infarction under stable experimental conditions, a repetitive measurement of regional myocardial flow should identify the temporal and spatial evolution of ischemic myocardial damage. Therefore transfemoral intraluminal occlusion of the LAD was used to produce myocardial infarcts in 9 dogs. The animals were kept on the respirator under light anesthesia for 24 hrs. Radioactive microspheres were used to determine regional myocardial flow at 0.2, 12, and 24 hours post occlusion. Infarct size was determined by p-NBT staining and expressed as per cent perfusion area, as determined by post mortem angiography after comparative planimetry. The results indicated a 75+12% infarction of the perfusion area at risk after 24 h, 61+18% of the epicardial, 83+13% in the endocardial sections. The flow after24 h in 93% of the infarcted tissue was <= 10 ml/lOO/min-l. Therefore this amount of flow was considered to identify the tissue at risk. At 0.2 h post occlusion 19.2% of the epicardial tissue exhibited flows Cl0 ml/lOO/min-l as compared to 66% of the endocardial sections, at 12 h 30% and 788, and at 24 h 61% and 88% respectively. The data indicate that under the given experimental conditions, a threshold flow value can be used to identify tissue damage and to observe a transmural evolution of myocardial infarction.

THE

CHARACTERIZATION

CARDIUM Cardiothoracic England.

are and

function. myocordium technique “intact”

BY

Institute,

Mitochondrial dation) tissue

OF

DAMAGED

In order of rats utilizing were

techniques

to characterize treated with a discontinuous (78%

isolated

the

mitochandria (This

work

fraction isolation and

was

do not

supported

and

more

Street,

in

RAT

MYO-

Alan

J. Williams.

London,

WIN

or enzyme

mitochondria mitochandrial

(inner

reflect

the

membrane) material and

morphology were similar

the

true

Viscount

mitochondrial

2DX,

degra-

from cardiac structure and

fragments

of isoprenaline

of the sucrose gradient. techniques always select

by

and

centrifugation

well functioning alterations

myocardium

study mitochandrial structure. The isolated by conventional techniques dense

FROM

Grieve

2 Beaumont

(differential

of control)

from

J.

the mitochondrial ch nges that occur in the -9 t.d.s. isoprenaline (25 mg.kg for2days) an isolation sucrose gradient (1.70M - 1.80M) was used. Fewer

enzymes succinate dehydrogenase were used as markers of mitochcndrial

the most conventional

ISOLATED Susan

of London,

to isolate “intact” suitable for studying

mitochondria

of control)

University

isolation designed are not

MITOCHONDRIA

ISOPRENALINE.

spectrum Royston

treated

rats.

(105 - 1390/a The

and malate dehydrogenase electron microscopy was

(matrix) used to

and enzyme activity to those of “intact”

of mitochondria mitochondria

It appears, therefore, the same population

that of “intact”

of mitochondrial Memorial

Fund).

damage.

on