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Alterations in myocardial hydrogen ion concentration after temporary coronary occlusion: a sign of irreversible cell
Insights
Myocardial hydrogen ion (H+) concentration increases during coronary occlusion, indicating the no-reflow phenomenon. Alkaline reactions in heart muscle tissue signify irreversible cell damage, even after blood flow restoration.
Area of Science:
- Cardiovascular Physiology
- Myocardial Pathophysiology
- Biochemistry
Background:
- Temporary coronary occlusion leads to significant changes in myocardial tissue.
- Understanding the ionic shifts during and after ischemia is crucial for assessing tissue viability.
Purpose of the Study:
- To investigate alterations in hydrogen ion (H+) concentration in feline myocardium following temporary coronary occlusion.
- To determine the relationship between pH changes, the no-reflow phenomenon, and irreversible myocardial damage.
Main Methods:
- Myocardial pH was assessed using pH indicator paper on frozen heart sections in cats.
- Measurements were taken at various time points before, during, and after coronary occlusion of different durations.
Main Results:
- Elevated H+ concentration (acidic pH) was observed transmurally in the left ventricle before occlusion release, confirming the no-reflow phenomenon.
- Alkaline pH in border zones correlated with longer occlusion times and persisted after reperfusion.
- Muscle cell necrosis developed in alkaline-reacting areas, suggesting these indicate irreversible damage.
Conclusions:
- The no-reflow phenomenon is characterized by increased myocardial H+ concentration during temporary coronary occlusion.
- An alkaline shift in myocardial pH is an early indicator of irreversible muscle cell damage, even after reperfusion.
Abstract:
Alterations of hydrogen ion (H+) concentration in the myocardium of 60 cats were determined before release of coronary ligation of 30, 45, 60, 90 or 180 minutes' duration, or 5, 30 and 90 minutes after release of the occlusion, by pressing pH indicator paper on unfixed frozen heart sections. The H+ concentration had clearly increased (pH less than 6.0) in a transmural extension in the left ventricle before release of the coronary ligature. This elevated H+ concentration persisted some time in the subendocardial region despite release of the coronary occlusion, thus proving that the so-called no reflow phenomenon exists in involved myocardium after temporary coronary occlusion. A diminished H+ concentration (pH 7.4) was found in the border zone between the acid-reacting area and the normal muscle when the coronary occlusion lasted 180 minutes before release of the ligature or 30 minutes after release of the occlusion when the previous period of temporary occlusion had been longer than 30 minutes. Although areas manifesting an acid reaction vanished or diminished in size after release of coronary occlusion, the extent of alkaline-reacting zones showed no reduction in size, and muscle cell necrosis developed in these alkaline-reacting areas. It is assumed therefore that an alkaline reaction of the myocardium is an early sign of irreversible muscle cell damage.