QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by FERGUSON, R. A. Articles by STOREY, K. B. Search for Related Content PubMed Articles by FERGUSON, R. A. Articles by STOREY, K. B. Social Bookmarking                         What's this?

Journal of Experimental Biology 155,469-485 (1991)
Published by Company of Biologists 1991

Glycolytic and Associated Enzymes of Rainbow Trout (Oncorhynchus Mykiss) Red Cells: In Vitro and In Vivo Studies

RALPH A. FERGUSON ¹ and KENNETH B. STOREY ¹

¹ Institute of Biochemistry and Department of Biology, Carleton University, Ottawa, Ontario, Canada K1S 5B6

To whom reprint requests should be addressed

Studies were undertaken in vitro and in vivo to assess the maximal activities of 26 glycolytic and associated enzymes of rainbow trout (Oncorhynchus mykiss) red cells. The red cells possess a complete sequence of glycolytic enzymes capable of anaerobic oxidation of glucose to lactate. Red cell pyruvate kinase (PK) was inhibited by ATP (I₅₀ 5 mmol l^-1), but was not sensitive to alanine inhibition or fructose-1,6-bisphosphate activation. The properties of red cell PK were similar to those of the muscle-type enzyme. Lactate dehydrogenase (LDH) from the trout erythrocyte resembled LDH from trout heart in terms of pyruvate inhibition in vitro. Enzymes associated with phosphagen and amino acid metabolism as well as the pentose phosphate shunt were also present. However, enzyme indicators of glycogenolytic and gluconeogenic potential were either absent or present at very low levels. The capacity for aerobic respiration via the tricarboxylic acid (TCA) cycle was suggested by the presence of citrate synthase activity.

The association of glycolytic enzymes with the particulate fraction of the red cell was assessed for six enzymes. No binding was detected for hexokinase, PK and LDH; low levels of binding by phosphofructokinase (5%), aldolase (1%) and glyceraldehyde-3-phosphate dehydrogenase (3%) were not altered by strenuous exercise. Glycolytic enzyme binding, therefore, does not appear to be an important regulator of energy metabolism in these cells. Intracellular glucose levels, in contrast, appeared to be regulated following exercise stress. An increase in intra-erythrocytic lactate levels at this time may reflect the importance of exogenously produced lactate as a substrate for ATP production. The description of trout red cell metabolism presented here provides a basis for further study of the relationships between organismic gas exchange and molecular-level adaptation of nucleated red cell function.

Key words: red blood cell, rainbow trout, Oncorhynchus mykiss, glycolysis, glucose, lactate, Enzymes, exercise

Accepted on August 31, 1990

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?