High titer antibody to mammalian neuronal sodium channels produces sustained channel block.

Antibodies specific for neuronal sodium channels recognized the alpha and beta subunits of the voltage-gated sodium channel on immunoblots of crude rat and cat brain membranes and purified rat brain sodium channels. These antibodies did not recognize channels from rat cardiac or rabbit skeletal muscle. Antibody binding to blots of crude rat brain membranes was blocked by preabsorption of the antibody with purified rat brain sodium channels. Staining of the sodium channel alpha subunit on immunoblots of crude rat brain membranes was easily visualized at antibody dilutions of up to 1:150,000, which is at least 15-fold higher than that reported in previous studies. Addition of antibody produced in one chicken to the extracellular face of batrachotoxin-activated rat brain sodium channels in planar lipid bilayers produced a sustained block of the channel at either hyperpolarized (-65 to -45 mV) or depolarized potentials (+45 to +75 mV). This block was not produced when the antibody was added to the cytoplasmic face of the channel, or if preimmune antibody was added to the extracellular face of rat brain sodium channels.

Erythrocyte deformation in ischemic acute tubular necrosis and amelioration by splenectomy in the dog.

Bilateral renal artery occlusion (RAO) for 120 minutes in dogs results in acute tubular necrosis (ATN) and peritubular capillary (PTC) congestion with rapidly deteriorating renal function. We have shown that prior splenectomy minimizes RAO-induced renal functional and histopathologic changes. The purpose of this study was to examine whether this renal protection is due to prevention of red blood cell echinocyte formation and resultant renal PTC congestion. Echinocytes (burr cells) are poorly deformable, impart high viscosity to the blood, and may hinder reperfusion by increasing resistance to renal capillary blood flow. Splenectomized (SPLX) or sham-SPLX dogs were treated with bilateral RAO for 120 minutes. After RAO, renal function and renal blood flow were monitored, and peripheral blood red blood cells were examined at 1 hour and at 24-hour intervals for 96 hours. Renal biopsies were taken 1 hour after RAO and the kidneys removed 96 hours after RAO. The RBCs and renal tissues were studied using scanning electron microscopy. Renal function was assessed by endogenous creatinine clearance. Sham-SPLX animals showed a marked and sustained decrease in creatinine clearance, consistently elevated serum creatinine levels and fractional excretion of sodium, and diffuse ATN and PTC congestion with echinocytes. These animals had a peak in circulating echinocytes 1 hour after RAO (p less than 0.05), which showed an excellent negative correlation with creatinine clearance (r = -0.999; p less than 0.001). On the contrary, SPLX animals had essentially no change in serum creatinine or fractional excretion of sodium, minimal tubular changes, no PTC congestion, and no rise in circulating echinocytes during the 96-hour observation. In vitro treatment of the postischemic red blood cells from sham animals with adenosine-inosine or fresh postischemic plasma from the SPLX animals showed almost complete reversal to discocytes (normal red blood cells), whereas in vitro treatment of postischemic red blood cells from the SPLX animals with fresh postischemic plasma from the sham animals resulted in a marked echinocytic response. We conclude that 1) a marked echinocyte response in the immediate postischemic period is an important mechanism in initiating ischemic ATN, 2) an echinocyte inducing factor may reside in the plasma of spleen-intact animals, and 3) mitigation of ATN and PTC congestion by splenectomy is, at least in part, consequential to attenuated echinocytic response in the immediate postischemic period.