Host cell utrastructure and nerve barriers impairing early CMI-based recognition of and adequate drug access to intraneural leprosy bacilli

Abstract

Calcium transfer across the blood-nerve barrier of the frog sciatic nerve was studied using an in situ perfusion technique and an in vivo i.v. bolus injection technique. The permeability-surface area product of45Ca at the blood-nerve barrier, (PA)BNB, calculated from radioactivity in the desheathed nerve segment after 5 min of circulation of tracer, and corrected for the residual radioactivity in the blood space, equaled4.4 ± 0.4 (S.E.M.) × 10−5ml· g−1 wet wt. The (PA)BNBof45Ca was independet of [Ca2+]in the perfusion medium between 0.18 and 18mM. The permeability-surface area products of45Ca across the perineurium [(PA)per] also was measured by an in situ incubation technique, and equaled1.45±0.41 × 10−5ml·s−1·−1 wet wt. (n=8). The half time (t1/2) for nerve calcium to equilibrate with plasma calcium was calculated to be 60 min. The low, passive permeability to calcium of the blood-nerve barrier probably limits marked calcium concentration changes in nerve endoneurium following transient changes of plasma calcium, but should not alter steady-state responses.