Interrelationships among platelet responses: studies on the burst in proton liberation, lactate production, and oxygen uptake during platelet aggregation and Ca2+ secretion.

The interrelationships between several functional and metabolic platelet responses to physiologic stimuli have been studied in gel-filtered platelets by continuous and simultaneous registration of shape change. aggregation. Ca2 secretion, oxygen uptake. and proton liberation. At various rates of aerobic and anaerobic energy metabolism. proton liberation quantitatively paralleled the production of lactate. However. immediately following thrombin addition. a lactate-unrelated burst in proton liberation became apparent. which correlated with acid hydrolase secretion but not with dense granule or a-granule secretion. ATP-hydrolysis. or hydrolysis of membrane constituents. Following platelet stimulation with a low dose of thrombin (0.1 U .m11), a specific order of cellular responses was recorded: (1 ) onset of shape change; (2) acceleration of lactate-related proton liberation; (3) onset of aggregation; (4) onset of Ca2 secretion; and (5) a minor increase in oxygen uptake. Stimulation with a high dose of