In vitro effects of somatostatin on red cell filterability measured by three methods

Somatostatin is an ubiqutary neuropeptide and hormone which has been reported to exert hemodynamic effects and to bind to receptors on the red cell membrane. We investigated its effects on red cell deformability by three filtration methods: (a) filtration of red cells resuspended at hematocrit 8% in Tris-Albumin-Glucose buffer under atmospheric pressure; (b) filtration of red cells resuspended at hematocrit on native plasma at 8% hematocrit under a negative pressure of 5 cm of water; (c) filtrability of whole blood under a negative pressure of 20 cm of water. Aprotinin (Antagosan*) was added to the different suspensions in order to avoid rapid destruction of somatostatin. Increased quantities of somatostatin (from 1 pg/ml to 1 microgram/ml) were obtained by adding natural somatostatin (Modustatin*) to the media, before they were incubated at 37 C for 30 minutes. In 11 samples from healthy subjects, somatostatin was shown to increase red cell flow rate in technique (c) (+ 118%, p less than 0.05) and to reduce red cell rigidity index in technique (b) (- 71%, p less than 0.025) whereas a nonsignificant similar tendency (- 56%) was observed with technique (a). Similar results (p less than 0.05) are observed when adding somatostatin to blood of diabetics. These in vitro data suggest that somatostatin, like other previously studied hormones, may modify red cell deformability.