Summary
A Comparative Study of Diagnostically Important Enzymes in Blood Plasma, Udder Lymph and Milk of Healthy and Udder Disease Infested Cows
Different secretions (colostrum, milk, dry udder secretion) of every quarter, peripheral lymph from superficial lymph vessels of the mammary gland and blood from the V. epigastrica superficialis were obtained in 43 cows at different stages of lactation. In these samples the activity of 5 enzymes (LDH, NAG, AP, LAP, GGT) was determined. Levels of LDH and NAG were highest in blood plasma and udder lymph. Levels of LAP, AP and GGT were highest in milk increasing in this order. LDH, NAG, AP and LAP were correlated in both compartments. Changes of the functional state (dry or colostral period) and tissue disturbances of the mammary gland were accompanied by marked changes of enzyme activity in the secretions, but were without obvious influence on enzyme levels in blood plasma and udder lymph.
Zusammenfassung
Bei 43 Kühen in verschiedenen Laktationsstadien wurde beim morgendlichen Melken aus jedem Euterviertel das Sekret (Kolostrum, Milch, Trockenstehersekret) und anschließend periphere Euterlymphe aus den oberflächlichen Lymphgefäßen sowie Blut aus der V. epigastrica superficialis entnommen. In den Eutersekreten und in Lymph‐ und Blutplasma wurde die Aktivität von 5 Enzymen (Laktatdehydrogenase [LDH], N‐Azetyl‐β‐D‐glucosaminidase [NAG], alkalische Phosphatase [AP], Leuzinaminopeptidase [LAP], gamma‐Glutamyltransferase [GGT]) ermittelt. LDH und NAG sind vorwiegend in Blutplasma und Euterlymphe enthalten, LAP, AP und GGT in steigendem Grad in der Milch. Bei LDH, NAG, AP und LAP bestehen Korrelationen zwischen beiden Verteilungsräumen. Veränderung des Funktionszustandes des Euters (Trockenstellen, Kolostrumbildung) und Schädigung des Eutergewebes bei Mastitis verändert nur die Enzymaktivität in den Eutersekreten tiefgreifend, ist aber ohne wesentlichen Einfluß auf die in Blutplasma bzw. Euterlymphe.
In liver cell membranes of laying hens a,-adrenergic receptors were characterized using 'H-prazosin. Specific binding was saturable and indcative of a single class of high-affinity binding sites with a KO of 0.40 f 16 nM and a B, , , of 390 f 38 fmol/mg membrane protein. Preincubation of membranes with chlorethylclonidine significantly diminished the binding of 'H-prazosin ( B , , , = 99 f 14 frnol/mg rnernbrane protein). Furthermore, competition experiments revealed a rank order of prazosin >> phentolamine = oxymetazoline >> WB 4101, with K, values of 0.71 f 0.62,20 f 6, 32 f 13, and 119 & 48 nM, respectively. These results suggest the existence of a,,-adrenergic receptors in hen liver cell membranes.
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