One of you caught an error in slide 18 of Dr. Dolan’s presentation:
The last bullet states that too much cytoplasmic calcium inhibits cellular enzymes – but actually, it activates cellular enzymes. Check out this diagram from Robbins (Dr. Dolan’s slide 19):
Increased cytoplasmic calcium does a lot of bad stuff, and the first steps along those pathways are 1) activation of cellular enzymes and 2)increased mitochondrial permeability. So here is the corrected version of slide 18:
Q. Would it be correct to say that increase in cytoplasmic calcium due to disrupted mitochondrial oxidative phosphorylation is reversible, whereas increase in cytoplasmic calcium due to membrane damage is irreversible? That is the impression I am getting from the slides and diagrams. Or are things more nuanced than this?
A. I think that your statement is accurate. That might be a little more in depth than we need to get into – but I am impressed by the degree to which you’ve studied and assimilated the concepts in the diagrams! I think it’s enough to know that if you have a massive influx of calcium, the cell is most likely going to go down the irreversible injury pathway. But you’re right; you need to damage the cell membrane to get an influx of calcium of that magnitude.