Enzyme Activities and Protein Concentration in the Intraocular Fluids of Ten Mammals

Abstract

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.

Lysosomal Phospholipase A2 Activity in Pig Aqueous Humor

“…LDH activities in the AHs of six other mammalian species (no electrocution) ranged from 3.6 U/L (dog) to 8.5 U/L (rabbit). 26 The value of our pig AH is close to that of those mammalians. Furthermore, we did not detect LAMP-1 in pig AH by Western immunoblot analysis (data not shown).…”

“…To assess pig ocular tissue damage, the lactate LDH activity of pig AH was examined. The activity was 10.3 Ϯ 3.11 U/L (mean Ϯ SD; n ϭ 4), which is a much lower value than that (115 U/L) reported by Wurster et al 26…”

“…LDH is a cytosolic enzyme and a useful marker for assessing cell membrane damage. The LDH activity of pig AH was 10.3 Ϯ 3.11 U/L (mean Ϯ SD; n ϭ 4), which is about one tenth of that reported by Wurster et al 26 They pointed out that the high value of LDH activity in their pig AH may be due to the special mode of killing the animal (electrocution). Also, the with negatively charged lipid membrane is very weak at neutral pH.…”

Direct effect of light on 24-h variation of aqueous humor protein concentration in Sprague–Dawley rats

“…The widely used Sprague-Dawley rat has a daytime aqueous humor protein concentration of approximately 1.00 mg/ml (Stjernschantz et al, 1973); higher than the 0.12 - 0.52 mg/ml aqueous humor protein concentrations in all other species studied including humans (Wurster et al, 1982; Tripathi et al, 1989), cattle (Wurster et al, 1982), horses (Wurster et al, 1982), sheep (Wurster et al, 1982), dogs (Wurster et al, 1982; Krohne et al, 1995), cats (Buco et al, 1978; Wurster et al, 1982), rabbits (Wurster et al, 1982; Liu, 2002), and mice (Zhou and Liu, 2006). This high concentration in rats may reflect a direct effect of light exposure on aqueous humor protein level.…”