Key result
Excess ionic calcium and/or magnesium above normal levels additively inhibit human platelet aggregation, whereas the calcium/magnesium ratio is important at low ionic concentrations.
This basic science study demonstrates that while low levels of calcium are sufficient for platelet aggregation, excess calcium and magnesium have additive inhibitory effects.
Offers mechanistic insight into platelet modulation; leaves open translation to human thrombosis or therapy.
The ionic calcium requirement for platelet aggregation is much lower than that required for fibrin formation. Maximal aggregation can still take place with the [Ca2+] well below 5 × 10−6M. Chelation of Ca2+ with EGTA results in a decrease in aggregation at a higher [Ca2+] than when EDTA is employed. This seems to indicate that the [Ca2+]/[Mg2+] ratio may be of importance at low ionic concentrations. However, excess [Ca2+] and/or [Mg2+] above the normal levels inhibit aggregation. In fact, when both of these ions are added in excess of the normal levels their inhibitory effects are additive, indicating that the [Ca2+]/[Mg2+] ratio is of little consequence under these conditions.
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Herrmann et al. (1970) studied Platelet aggregation. Ionic Calcium and Magnesium vs. Normal levels was evaluated on Platelet aggregation. Excess ionic calcium and/or magnesium above normal levels additively inhibit human platelet aggregation, whereas the calcium/magnesium ratio is important at low ionic concentrations.
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