719 PRESERVATION OF BRUSH BORDER MEMBRANE ALANINE TRANSPORT IN ACUTE VIRAL DIARRHEA

Abstract

To further characterize mechanisms of viral diarrhea, we assessed ³H-alanine uptake into small intestinal brush border membrane vesicles (BBMV) from piglets after experimental infection with transmissible gastroenteritis (TGE) virus. With a 100mM NaCl gradient, accumulation ratios (alanine uptake from 5 sec to 4 min ÷ equilibrium uptake at 4 hrs) were equivalent in control & TGE BBMV. Maximal “overshoots” were equivalent (1.7±0.1 x in control & 1.9±.3 x in TGE BBMV). ³H glucose accumulation ratios, as before (Gastro. 80:1191, 1981), were blunted (p<.01) in TGE BBMV. These results agree with our Ussing chamber data suggesting more than 1 co-transporting BBM system in TGE epithelium. Short-circuited TGE jejunum demonstrated a greater increment (p<.05) of net_Na ²²Na absorption after alanine (50mM) plus glucose (30mM) (ΔJnet-3.3 ±0.4 uEq/cm²/hr) than after optimal concentrations of either alanine (50mM)₂ (ΔJnet=0.8±0.6 uEq/cm²/hr) or glucose (30mM) (ΔJnet=l.7±0.5 uEq/cm²/hr). We conclude a) Na gradient-dependent BBM alanine transport is relatively preserved in crypt-type epithelium characterizing viral enteritis and b) the blunted response of net Na flux to alanine in TGE tissue in Ussing chambers (Gastro. 86:128, 1984) is not a brush border phenomenon. Since TGE closely resembles human rotavirus enteritis, we suggest that our findings are relevant to the formulation of improved oral rehydration treatment solutions for infant diarrhea.

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