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Titolo:
RESPONSES OF THE RED-BLOOD-CELLS FROM 2 HIGH-ENERGY-DEMAND TELEOSTS, YELLOWFIN TUNA (THUNNUS ALBACARES) AND SKIPJACK TUNA (KATSUWONUS-PELAMIS), TO CATECHOLAMINES
Autore:
LOWE TE; BRILL RW; COUSINS KL;
Indirizzi:
NMFS,2570 DOLE ST HONOLULU HI 96822 UNIV HAWAII MANOA,SCH OCEAN & EARTH SCI & TECHNOL,JOINT INST MARINE &ATMOSPHER RES HONOLULU HI 96822
Titolo Testata:
Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology
fascicolo: 6, volume: 168, anno: 1998,
pagine: 405 - 418
SICI:
0174-1578(1998)168:6<405:ROTRF2>2.0.ZU;2-8
Fonte:
ISI
Lingua:
ENG
Soggetto:
TROUT SALMO-GAIRDNERI; ACID-BASE REGULATION; FLOUNDER PLATICHTHYS-STELLATUS; HEMOGLOBIN-OXYGEN-AFFINITY; CARBON-DIOXIDE TRANSPORT; ACUTE TEMPERATURE-CHANGE; CARP CYPRINUS-CARPIO; RAINBOW-TROUT; ONCORHYNCHUS-MYKISS; ADRENERGIC RESPONSES;
Keywords:
ADRENALINE; NORADRENALINE; NA+/H+ ANTIPORTER; OXYGEN; RBC;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
100
Recensione:
Indirizzi per estratti:
Citazione:
T.E. Lowe et al., "RESPONSES OF THE RED-BLOOD-CELLS FROM 2 HIGH-ENERGY-DEMAND TELEOSTS, YELLOWFIN TUNA (THUNNUS ALBACARES) AND SKIPJACK TUNA (KATSUWONUS-PELAMIS), TO CATECHOLAMINES", Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology, 168(6), 1998, pp. 405-418

Abstract

In fishes, catecholamines increase red blood cell intracellular pH through stimulation of a sodium/proton (Na+/H+) antiporter. This response can counteract potential reductions in blood O-2 carrying capacity (due to Bohr and Root effects) when plasma pH and intracellular pH decrease during hypoxia, hypercapnia, or following exhaustive exercise. Tuna physiology and behavior dictate exceptionally high rates of O-2 delivery to the tissues often under adverse conditions, but especially during recovery from exhaustive exercise when plasma pH may be reduced by as much as 0.4 pH units. We hypothesize that blood O-2 transport during periods of metabolic acidosis could be especially critical in tunas and the response of rbc to catecholamines elevated to an extreme. Wetherefore investigated the in vitro response of red blood cells from yellowfin tuna (Thunnus albacares es) and skipjack tuna (Katsuwonus pelamis) to catecholamines. Tuna red blood cells had a typical response to catecholamines, indicated by a rapid decrease in plasma pH. Amiloride reduced the response, whereas 4,4'diisothiocyanatostilbene-2,2'-disulphonic acid enhanced both the decrease in plasma pH and the increasein intracellular pH. Changes in plasma [Na+], [Cl-], and [K+] were consistent with the hypothesis that tuna red blood cells have a Na+/H+ antiporter similar to that described for other teleost red blood cells. Red blood cells from both tuna species were more responsive to noradrenaline than adrenaline. At identical catecholamine concentrations, the decrease in plasma pH was greater in skipjack tuna blood, the more active of the two tuna species. Based on changes in plasma pH, the response of red blood cells to catecholamines from both tuna species was less than that of rainbow trout (Oncorhynchus mykiss) red blood cells, but greater than that of cod (Gadus morhua) red blood cells. Noradrenaline had no measurable influence on the O-2 affinity of skipjack tuna blood and only slightly increased the O-2 affinity of yellowfin tuna blood. Our results, therefore, do not support our original hypothesis. The catecholamine response of red blood cells from high-energy-demand teleosts (i.e., tunas) is not enhanced compared to other teleosts. There are data on changes in cardio-respiratory function in tunas caused by acute hypoxia and modest increases in activity, but there are no data on the changes in cardio-respiratory function in tunas accompanyingthe large increases in metabolic rate seen during recovery from exhaustive exercise. However, we conclude that during those instances wherehigh rates of O-2 delivery to the tissues are needed, tunas' ability to increase cardiac output, ventilation volume, blood O-2 carrying capacity, and effective. respiratory (i.e., gill) surface area are probably more important than are the responses of red blood cells to catecholamines. We also use our data to investigate the extent of the Haldaneeffect and its relationship to blood O-2 and CO2 transport in yellowfin tuna. Yellowfin tuna blood shows a large Haldane effect; intracellular pH increases 0.20 units during oxygenation. The largest change in intracellular pH occurs between 40-100% O-2 saturation, indicating that yellowfin tuna, like other teleosts, fully exploit the Haldane effect over the normal physiological range of blood O-2 saturation.

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Documento generato il 23/09/20 alle ore 08:46:24