Adrenergic supersensitivity of rabbit choroidal blood vessels after sympathetic denervation

Abstract

Purpose. To demonstrate the phenomenon of adrenergic denervation supersensitivity in rabbit choroidal blood vessels after superior cervical ganglionectomy. Methods. Twenty four albino rabbits of both sexes weighing 2–3 kg were randomly separated into two groups. Twelve rabbits received bilateral superior cervical sympathectomy 2 weeks prior to the study (group s). The other 12 rabbits served as controls (group n). Four different concentrations of 0.1 ml phenylephrine, 0.05%, 0.025%, 0.013%, and 0.007% were slowly injected into the vitreous body near the retinal surface in group n and s rabbits (n = 6 in each group). The choroidal blood flow (PF), blood volume (CMBC), and velocity (V) were measured simultaneously by laser Doppler flowmetry (Perimed, PF 4001). Results. The PF showed similar decreases in group n and srabbits after injection of 0.05%, 0.025%, and 0.013% phenylephrine. With 0.007% phenylephrine, the PF remained unchanged in group n rabbits, but decreased significantly in group s rabbits (p = 0.0007). Velocity decreased similarly in both group n and s rabbits except for the 0.007% phenylephrine, concentration in which velocity decreased significantly in group s rabbits (p = 0.0001). There was no statistical difference in CMBC between group n and s rabbits at any of the test concentrations. Conclusions. The difference in PF decrease between group n and s rabbits with 0.007% phenylephrine demonstrated the existence of choroidal blood vessel denervation supersensitivity. The decrease in PF was achieved mainly through a decrease in blood cell velocity.