The method also combined measurement of changes in Ca2+i using fluo-4 and excitation at 490 nm. Results:  After establishing loading conditions, a linear relationship was demonstrated between Em and fluorescence signal in FRET dye-loaded HEK cells held under voltage clamp. Over the voltage range from −70 to +30 mV, slope (of FRET signal vs. voltage, m) = 0.49 ± 0.07, r2 = 0.96 ± 0.025. Similar data were obtained in cerebral artery SMCs, slope (m) = 0.30 ± 0.02, r2 = 0.98 ± 0.02. Change in FRET emission ratio over the holding potential of −70 to +30 mV was 41.7 ± 4.9% for HEK cells and 30.0 ± 2.3%

for arterial SMCs. The FRET signal was also shown to be modulated by KCl-induced depolarization BAY 73-4506 in vitro in a concentration-dependent manner. Further, in isolated arterial SMCs, KCl-induced depolarization (60 mM) find more measurements occurred with increased fluo-4 fluorescence emission (62 ± 9%) and contraction (−27 ± 4.2%). Conclusions:  The data support the FRET-based approach for measuring changes in Em in arterial SMCs. Further, image-based measurements of Em can be combined with analysis of temporal changes in Ca2+i and contraction. “
“Please cite this paper as: Zhang (2011). Effect

of Suspending Viscosity on Red Blood Cell Dynamics and Blood Flows in Microvessels. Microcirculation 18(7), 562–573. To obtain a better understanding of the beneficial effect of high plasma viscosity observed in hemodilution and resuscitation experiments, we conducted a computational study to investigate

the suspending viscosity effect on red blood cell (RBC) dynamics and blood flow behaviors in microvessels. For single RBCs in simple shear or channel flows, RBCs appear more flexible as indicated by the tank-treading motion in shear flows and the strong transverse migration in channel flows. For the multiple RBC flows in straight channels, our results indicate no significant change with the suspending viscosity in stable flow structure and hemorheologic behaviors, under both constant Calpain flow and forcing conditions. However, due to the increase in apparent cell deformability in a more viscous medium, the cell-free layer (CFL) can be established in a shorter distance along the channel. Considering the multilevel bifurcated structure of the microvascular network, this change in CFL development distance may affect the phase skimming and RBC separation processes at the downstream bifurcation, and therefore the microcirculation performance in the tissue. This may suggest a possible mechanism for the high functional capillary density associated with a high suspending viscosity observed in experiments. “
“Please cite this paper as: Folkesson KT, Samuelsson A, Tesselaar E, Dahlström B, Sjöberg F.