PURPOSE In this paper, Magnetic Resonance Imaging, peripheral iridectomy, tracer localization methods were combined to further verify the existence of a pathway in the normal rabbit for the diffusion of proteins from the ciliary and iridial process stromas through the iris stroma into the aqueous humor of the anterior chamber.
METHODS The experiments were conducted with eight rabbits in vivo. These rabbits firstly received monocular peripheral iridectomy and the contralateral eyes acted as control eyes. After anesthetized, these rabbits were injected intravenously a new tracer Gadolinium-diethylene triamine pentaacetic acids (Gd-DTPA) with Gd-DTPA (0.5%mol/L, 0.2ml/Kg). The permeability and distribution of the tracer were determined by spin-echo MR imaging(MRI).
RESULTS In all cases, signal intensity rose rapidly in the ciliary body, hereafter decreased gradually over time. In all subjects, there was a measurable slowly rise in signal strength (enhancement) in the anterior chamber, with ciliary body signal enhancement, and signal peak was later than that of ciliary body. Increased signal within the posterior chamber was significantly less than in the anterior chamber in contrast eyes, moreover, these signals were increased synchronously in experimental eyes.
CONCLUSIONS These findings are consistent with the existence of an anterior diffusional pathway in the rabbit eye. The channel of plasma protein entered into the anterior chamber was different from that of aqueous secretion. There was barrier between the anterior and posterior chamber which might be an integral part of the blood-ocular barrier and that might have important physiological significance. |
