Effects of verapamil on calcium-induced rigidity and on filterability of red blood cells from healthy volunteers and patients with progressive systemic sclerosis.

The effects of verapamil on calcium-induced decrease deformability of red blood cells (RBCs) and on the filterability of RBCs from healthy volunteers and patients with progressive systemic sclerosis (PSS) were investigated in vitro using a gravity driven filtration technique. The filterability of RBCs was increased by verapamil 1 microgram/ml (P less than 0.01) in healthy volunteers (P less than 0.05) and in patients with PSS (P less than 0.05). A high concentration of verapamil (200 micrograms/ml) caused an 80% reduction (P less than 0.05) in the filterability of RBCs from healthy volunteers. The filterability of RBCs stored at 4 degrees C for 24 h was increased by 1 microgram/ml verapamil (P less than 0.05). Verapamil (1 microgram/ml) prevented the decrease in deformability of RBCs due to an increase in either extracellular or intracellular calcium concentrations (P less than 0.05). By increasing red cell filterability verapamil may be useful in the treatment of PSS and other peripheral vascular diseases where decreased red cell deformability may play an important role in the pathogenesis.