Crosstalk between adenylyl cyclase signaling pathway and Ca 2+ regulatory mechanism under red blood cell microrheological changes

There are evidences that red blood cell (RBC) deformation and aggregation change under their incubation with catecholamines and it is connected with activation of intracellular signaling pathways. The present study was designed to explore the adenylyl cyclase signaling pathway and Ca²⁺ regulatory mechanism of RBCs together with their microrheological changes. The washed RBCs were resuspended in PBS. In each of the three research sessions RBC suspensions were divided into two aliquots: 1) control (without drug) and 2) with an appropriate drug. After cell incubation RBC deformability (RBCD) and aggregation (RBCA) were estimated. RBC incubation with catecholamines resulted in RBCD changes by 18–30%. RBCs incubation with forskolin facilitated an increase of RBCD by 17% (p < 0.05). A significant deformability rise under dB-AMP incubation was found by 27% (p < 0.01). Ca²⁺ cell influx, stimulated by A23187, was accompanied by an increase of RBCA; whereas red cell deformability was changed only slightly. On the other hand, Ca²⁺ entry blocking into the cells by verapamil has led to significant RBCA decrease and RBCD rise. The obtained results make us believe that RBCD change was closely associated with Ca²⁺ control mechanisms. An effect of Ca²⁺ concentration increase on RBC microrheology was removed, if it was preliminary added to incubation medium EGTA as Ca²⁺ chelator. It was found that all four PDE inhibitors: IBMX, vinpocetine, rolipram, pentoxifylline decreased RBCA significantly and, quite the contrary, they increased red cell deformability. Our data have shown that Ca²⁺ entry increase was accompanied by red cell aggregation rise, while adenylyl cyclase-cAMP system stimulation led to red cell deformability increase and its aggregation lowered. The crosstalk between two intracellular signaling systems is probably connected with phosphodiesterase activity.