title: Aqueous flow in humans after adrenalectomy.
abstract: OBJECTIVE
  This study was performed to determine if the circadian rhythm of aqueous humor formation and the aqueous humor suppressing effect of beta-adrenergic antagonists can occur in the absence of adrenally derived epinephrine.
  
  
  METHODS
  Twenty-one human subjects who had undergone bilateral adrenalectomy were studied during a 28-hour period. The study was divided into four time periods as follows: morning 1 (8 AM to noon), afternoon (noon to 4 PM), night (midnight to 6 AM), and morning 2 (8 AM to noon). At 6:45 AM before the morning 2 measurements, one drop of 0.5% timolol was applied to one eye and one drop of placebo (artificial tears) was applied to the other eye. Topical fluorescein and a scanning fluorophotometer were used to measure the rate of aqueous humor flow. Twenty normal controls were studied in a similar fashion but did not undergo the morning 2 measurement.
  
  
  RESULTS
  In the subjects lacking adrenals, the daytime rates of aqueous flow were 3.17 +/- 0.78 microliters/min (mean +/- SD) and 3.16 +/- 0.67 microliters/min for the morning 1 and afternoon periods, respectively. The rates in daytime periods were not significantly different from each other (P = 0.699). The rate of aqueous flow for the night period was 1.37 +/- 0.37 microliters/min, a 57% reduction from both morning 1 and afternoon periods (P < 0.001). The morning, afternoon, and night rates of flow in normal controls were not significantly different from the rates in subjects lacking adrenals. For the morning 2 period, the aqueous flow was 2.74 +/- 0.54 microliters/min for the placebo-treated eye and 1.77 +/- 0.38 microliters/min for the timolol-treated eye. The rate of aqueous flow was reduced (35%) in the timolol-treated eye when compared to the fellow placebo-treated eye (P < 0.001). The timolol-treated eye also showed a 26% reduction in intraocular pressure when compared to the fellow placebo-treated eye (P < 0.001).
  
  
  CONCLUSIONS
  The study demonstrates that both the circadian rhythm of aqueous flow and the daytime response to timolol persist in the absence of the adrenal glands.
authors.affiliation: Department of Ophthalmology, Mayo Clinic, Rochester, MN 55905.
authors.forename: T L
authors.initials: TL
authors.lastname: Maus
authors.forename: W F
authors.initials: WF
authors.lastname: Young
authors.forename: R F
authors.initials: RF
authors.lastname: Brubaker
mesh_terms: D000315:Adrenalectomy; D000328:Adult; D001082:Aqueous Humor / Q000502:physiology*; D002940:Circadian Rhythm; D004837:Epinephrine / Q000502:physiology; D015914:Estrogen Replacement Therapy; D015590:Fluorophotometry; D006801:Humans; D007429:Intraocular Pressure; D008875:Middle Aged; D009883:Ophthalmic Solutions; D013999:Timolol / Q000008:administration & dosage
chemical_list: D009883:Ophthalmic Solutions; D013999:Timolol; D004837:Epinephrine