Changes of Serum Alkaline Phosphatase Isoenzymes in Fasted Rats.

Abstract

SummaryChanges of serum alkaline phosphatase (sALP) isoenzymes under fasting conditions were examined using polyacrylamide gel electro phoresis (PAGE), amino-acids (L-phenylalanine (L-Phe), L-homoargi nine (L-HArg)) inhibition and wheat germ agglutinin (WGA) treatment. The sALP of non-fasted rats was separated into three bands (S1, S2, S3) by PAGE. The molecular weight (M.W.) of S1 corresponded to that of an isoenzyme found in the ileum. By the addition of L-Phe, the staining intensity of S1 was weakened, S2 and S3 remained unchanged and the total activity of the isoenzymes extracted from intestine decreased. On the other hand, the activity of isoenzymes extracted from kidney and bone decreased by the addition of L-HArg. Therefore, S1 was judged to be derived from intestine. The activities of total sALP and S1 decreased from 16h of fasting. Total sALP activity and sALP activity of the supernatant prepared by WGA treatment decreased, whereas the ALP activity of the precipitate (difference between total sALP activity and supernatant sALP activity) did not change. The activity band of the precipitate corresponded to that of S3 by PAGE. Therefore, S3 was judged to be derived from bone. In conclusion, under fasting conditions, the activity of S1 decreased while the activities of S2 and S3 remained unchanged.

Distribution and Properties of Rat Intestinal Alkaline Phosphatase Isoenzymes.

“…It is also found in serum [3] and several types of isoenzymes have been reported [7]. We previously reported that one of the serum isoenzymes disappeared under fasting conditions [17]. In addition, this particular isoenzyme was identified as one of the isoenzymes observed in the intestine intrinsically [18].…”

“…): PAGE was conducted using the solution extracted from each intestinal segment [17]. After PAGE of the supernatant solution, activity staining for ALP and protein staining were conducted.…”

“…The determination of the molecular weights (M.W.) of the isoenzymes was carried out according to a method previously described [17].…”

Tissue-nonspecific alkaline phosphatase is activated in enterocytes by oxidative stress via changes in glycosylation

“…As shown in Figure 1C, the rat AP isoforms characterized by high inhibition by levamisole include the kidney and bone variants, while those present in testes, liver, and the small intestine are resistant. 8,48 tButOOH in our hands was the most consistent of all the agents assayed and thus was selected for further experimentation. tButOOH induced AP activity starting at 300 lM but the sensitivity to levamisole (percent inhibition of basal AP activity) was augmented at lower concentrations (Fig.…”

“…6 Thus, the liver enzyme is more resistant to levamisole or homoarginine inhibition than either the kidney or bone isoforms. 5,7,8 The placental and intestinal enzymes have a 87%-90% similarity at the genomic level 9,10 and are generally similar in their sensitivity to chemical inhibitors, displaying only minor differences. [11][12][13][14][15] The placental isoform is reported to be the most resistant to heat as well as to inhibition by levamisole and homoarginine.…”