Thermoprotection of a functional epithelium: heat stress effects on transepithelial transport by flounder renal tubule in primary monolayer culture.
AUTOR(ES)
Brown, M A
RESUMO
Primary monolayer cultures of winter flounder renal proximal-tubule cells were used to determine whether transepithelial transport could be protected from the damaging effects of extreme temperature by previous mild heat shock. Renal tubule epithelial cells were enzymatically dispersed and reorganized as confluent monolayer sheets on native rat tail collagen. Transepithelial electrical properties (potential difference, resistance, short-circuit current, and Na(+)-dependent glucose current) and unidirectional [35S]sulfate fluxes were measured in Ussing chambers at 22 degrees C. Examination of transepithelial electrical properties following acute 1-hr elevation of temperature over a range of 22-37 degrees C provided the basis for the "mild" versus "severe" thermal stress protocols. Severe elevation from 22 degrees C to 32 degrees C for 1.5 hr followed by 1.5 hr at 22 degrees C significantly decreased glucose current (7 +/- 0.7 to 3 +/- 0.8 microA/cm2) as well as net sulfate secretion [131 +/- 11 to 33 +/- 11 nmol/(cm2.hr)]. Mild heat shock of 27 degrees C for 6 hr prior to this severe heat shock completely protected both glucose transport (6 +/- 0.7 microA/cm2) and sulfate flux (149 +/- 13 nmol/(cm2.hr)]. Scanning electron microscopy showed that the number of microvilli on the apical (luminal) surface of the epithelium was decreased after a 32 degrees C heat shock. Monolayers exposed to 27 degrees C for 6 hr prior to incubation at 32 degrees C showed no loss of microvilli. SDS/PAGE analysis of protein patterns from the cultures showed that three classes of heat shock proteins were maximally induced at 27 degrees C. Inhibition of protein synthesis by cycloheximide prevented the thermoprotective effect of mild heat shock. This suggests that certain renal transport functions can be protected from sublethal but debilitating thermal stress by prior mild heat shock and that heat shock proteins may play a role in this protection.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=48843Documentos Relacionados
- Transepithelial transport by pulmonary alveolar type II cells in primary culture.
- Transepithelial transport in cell culture.
- Growth state-dependent phenotypes of adult hepatocytes in primary monolayer culture.
- Regulation of pH in rat papillary tubule cells in primary culture.
- Cation transport by sweat ducts in primary culture. Ionic mechanism of cholinergically evoked current oscillations.