Membranolytic effects of crystalline monosodium urate monohydrate.

We studied the effect of heat treatment and subsequent rehydration of heated monosodium urate monohydrate (MSUM) crystals on the physicochemical characteristics and ability of the crystals to cause hemolysis of erythrocytes (measure of membranolytic potential). MSUM crystals dehydrated slowly on heating at 200 degrees from 1-5 h and rehydration to 100% monohydrate was complete within 30 min. Heating at 250 degrees for 2 h caused rapid dehydration to anhydrous MSU and rehydration was incomplete up to 17 h. Zeta potential and percent hemolysis of MSUM crystals decreased after heating and rehydration. This reduction in percent hemolysis may be due to the reduction in surface potential (measured as zeta potential) of the crystals.