Transfer of 45Ca and 36Cl at the blood-nerve barrier of the sciatic nerve in rats fed low or high calcium diets
✍ Scribed by Dr. K. C. Wadhwani; V. A. Murphy; S. I. Rapoport
- Publisher
- John Wiley and Sons
- Year
- 1991
- Tongue
- English
- Weight
- 372 KB
- Volume
- 28
- Category
- Article
- ISSN
- 0360-4012
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✦ Synopsis
Unidirectional fluxes of 45Ca, MCI, and of ['Hlmannitol from blood into the sciatic nerve and cerebral cortex were determined from 5-and 15-min uptakes of these tracers after an intravenous (i.v.) bolus injection in awake rats. Rats were fed diets for 8 wk, that had either a low (0.01% wt/wt), normal (0.67%), or high (3%) Ca content. Plasma [Ca] was 32% less and 11% more in rats fed low (LOCA) and high Ca diets (HICA), respectively, than in rats fed a normal Ca diet (CONT). The mean permeability-surface area product (PA) of 4sCa at the blood-nerve barrier was about eightfold higher than at the bloodbrain barrier in the same animals and did not differ significantly between groups (>0.05). Mean PA ratios of 45Ca/36CI for the blood-nerve and blood-brain barriers in CONT rats, 0.52&0.04 and 0.40+0.02, respectively, were not significantly different from corresponding ratios in LOCA and HICA groups, and corresponded to the aqueous limiting diffusion ratio (0.45). Our results show no evidence for concentration-dependent transport of Ca over a plasma [Ca] range of 0.8-1.4 mmol/liter at the blood-nerve barrier of the rat peripheral nerve, and suggest that Ca and C1 exchange slowly between nerve and blood via paracellular pathways.