The Henderson-Hasselbalch Equation : A Three Dimensional Teaching Model.

The Henderson-Hasselbalch equation can be considered as the backbone of acid base physiology. This is conventionally represented using two dimensional plots. Although two dimensional plots are simple to use, the equation in reality represents a surface in three dimensional space. Any combination of PaCO2, [HCO3 — ] and blood pH values representing acid base disorders is restricted to this surface. Two models depicting the three dimensional surface generated by the Henderson-Hasselbalch equation were constructed from easily available materials. The first model was constructed using coloured beads, thin metal rods and plywood. This model depicted the Henderson-Hasselbalch surface as a collection of discreet points. The second model depicted the Henderson-Hasselbalch equation as a continuous surface using polystyrene sheets and white cement. The models were presented to undergraduate and post-graduate medical students along with other conventional two dimensional nomograms. Three dimensional models of the Henderson-Hasselbalch equation can serve as supplementary teaching material to ensure a deeper understanding of acid base physiology.

Increase in voltage gated potassium currents of human lymphocytes on culture.

Voltage gated potassium channels present in T lymphocytes play an important role during lymphocyte activation. Though an increase in potassium currents has been reported in activated lymphocytes, changes in potassium currents in culture without activation by antigen or mitogen has not been reported. The peak potassium current densities on day 1 and day 5 of culture have been compared in this study. Peripheral blood mononuclear cells (PBMCs) were separated by density gradient centrifugation. Lymphocytes were separated from PBMCs by negative selection using anti-CD14 coated magnetic beads and cultured under appropriate conditions without antigenic or mitogenic stimulation. Lymphocytes were patched on day 1 or day 5 of culture. Voltage gated potassium currents were recorded by whole cell patch clamp technique using a depolarizing protocol. The mean of peak current densities recorded at +60 mV on day 1 of culture was 228.12± 89.39 pA/pF (n=7) and on day 5 of culture was 468.96 ± 192.07 pA/pF (n=7). The difference between the current densities on day 1 and day 5 was found to be significant. Change in electrophysiological characteristics can lead to functional changes in the lymphocytes and this should be considered when culturing lymphocytes in vitro for research and clinical use.