Histochemical Studies on the Effect of Anions on Alkaline Phosphomonoesterase Activity

Abstract

Pretreatment of cryostat sections of dog kidney with sodium salts of various anions in acetate buffer at pH 4.0 for periods of time ranging up to 6 hours produces differential inhibition of non-specific alkaline phosphatase activity as determined by the Gomori method. The degree of anionic effect is dependent on the nature of the anion and modified by the cation present. The effect also varies directly with the anionic concentration, duration of exposure and temperature of the pretreatment buffer and inversely with the pH. On the basis of the differential suppression of enzymatic activity by the various anions, and the conditions under which these effects were evident, distinctive inhibition profiles were established for the several phosphomonoesterases tested, including the renal and intestinal alkaline phosphatases and the smooth muscle 5'-nucleotidases of several species. The similarity of the results obtained in various biochemical studies on other enzymes reported in the literature and those obtained histochemically in these experiments suggests a common mechanism of action; this is presumed to be a differential effect of anions on the dissociation of apoenzyme and coenzyme. The method described provides a simple and effective means of differentiating, under histochemical conditions, closely related and even apparently identical enzymes.

Effect of Lactation and/or Calcium Deficiency on Cyclic-AMP Production and Bone Enzyme Activities in Rats: Lack of Effect of Long-Term Fluoride Administration

“…2], but a lack of effect of much higher dosage of fluoride (25 ppm) on urinary cAMP levels has also been shown [19], The effect of fluoride on cAMP levels in the plasma and bone, the major tis sue in the body where fluoride accumulates, have not been clearly elucidated. Although fluoride inhibits phosphatase activities in vi tro [5], administration of a moderate level of fluoride (50 ppm) to experimental animals in short-term in vivo studies did not depress bone alkaline phosphatase activity [17]. However, high doses of fluoride (200 ppm) increased bone alkaline phosphatase activity in rabbits [22] and the enzyme activity was elevated in cattle with chronic skeletal fluor osis [18].…”

“…Fluoride has been shown to affect many enzymes [24] including the stimulation of adenylate cyclase [21] and the inhibition of phosphatases [5] in vitro. The effect of fluo ride on adenosine 3'.5'-cyclic monophos phate (cAMP) production, and bone acid and alkaline phosphatase activities in vivo, how ever.…”