Enzyme activities and protein concentration in the intraocular fluids of ten mammals

An attempt was made to establish normal values for the total protein concentrations and the enzyme activities of LDH, MDH and PGI in the intraocular fluids of rats, guinea pigs, rabbits, cats, dogs, sheep, cattle, pigs, horses and humans. Remarkably little species differences were noted in 9 of the 10 mammals with vitreal enzyme activities falling into a narrow range between 8.4 U/l (PGI, horse) and 92.4 U/l (MDH, guinea pig). All species obeyed the sequence aqueous less than vitreous less than serum with exception of the rat, where vitreous activities surpassed serum at least two-fold. The very low enzyme activities in the aqueous and vitreous humors demand special precautions against contaminations which can either derive from post-mortem storage or inadequate sampling procedures. Conversely elevated enzyme activities could be used as probes for pathological processes or as a check for a clean preparation.