When visually assessing the myoplasmic [Ca2+] concentration and LVP signals befo

Question

When visually assessing the myoplasmic [Ca2+] concentration and LVP signals before and after ischemia, can you determine which of the two signals is leading/lagging the other? Does it make sense from a physiological standpoint? To answer this question, on your own research the relationship between these signals in the cardiovascular system. Make sure to include all valid references used. Before LVP and Calcuim in Prelschemia 300 250 150 100 50 0.5 1.5 2.5 time(s) After LVP and Calcuim in Postlschemia 400 350 300 250 2 200 150 100 0.5 1.5 2.5 time(s)

Explanation / Answer

The normal cardiac muscle contraction requires the influx of intracellular calcium from the sarcoplasmic reticulum . as shown in the fig 1 pre ischemic phase

But, during ischemia there is an elevated calcium levels .denominator of these events is an increase in the levels of intracellular free calcium (Ca2+ i ) the mechanism of this increase is not clear. The source of this elevation in Ca2+ i may include increased influx of calcium ions across the sarcolemma, enhanced release of Ca2+ from the sarcoplasmic reticulum (SR) and/or reduced transport of Ca2+ by the Ca2+-ATPase of the SR (SERCA2a) and the sarcolemmal Na+ /Ca2+ exchanger (NCX). Theoretically, the actual Ca2+ i level may also be affected by alterations in binding capacities of intracellular buffers (including Troponin C, SERCA2a, sarcolemmal binding sites, etc.) during I/R. The cyclic changes of Ca2+ i in the myocyte, i.e. the Ca2+ i transient, inherently contain information on handling of this ion within the cell. ,

Therefore in the given relationship the calcion concentration signals leads than the lvp post ischemia IN FIG 2..due to increased intracellular calcium levels.

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