Kjell Johansen

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Tilapia grahami (Boulenger), a small cichlid fish, inhabits extremely alkaline water where the total CO2 concentration exceeds 200 meq.L(-1), osmolality is about 600 mosm.L(-1), pH ranges between 9.6 and 10.5 and temperature may be 43 degrees C. Venous blood drawn anaerobically by heart puncture had pH values as high as 8.4 at 35 degrees C. A 10-15-fold(More)
1. Blood O2 transport and acid-base balance were studied at 20 degrees C in rainbow trout (Salmo gairdneri) which had been kept in water of high CO2 content (15 mmHg) for at least a week. Also the blood gas chemistry of fish rapidly entering or leaving the hypercapnic environment was studied. 2. Fish entering high CO2 water suffered a sharp decrease in(More)
A swim tunnel respirometer and an extracorporeal blood circulation technique allowed continuous collection of data from exercising fish below and near their critical speed. Swimming at speeds below maximum showed no changes in plasma Na+, Cl- and lactate concentrations but increased levels of blood hemoglobin and plasma K+. PaO2 and PaCO2 showed an(More)
Because it is so tall, the giraffe, Giraffa camelopardalis, provides an important animal model for investigating adaptive mechanisms to orthostatic (gravitational) pressure changes. Previous physiological studies of the giraffe have concentrated on arterial blood pressures in the heart and neck. Briefly, these investigations revealed that arterial pressure(More)
Gill ventilation, breathing frequency, breath volume, oxygen extraction from the ventilatory water current and oxygen uptake through the gills were measured in flounder, Platichthys flesus, and plaice, Pleuronectes platessa, at water O2 tensions ranging from 35 to 155 mm Hg at 10° C. Ventilation volumes were similar in the two species at high water O2(More)
Unlike the whole body oxygen affinity, which adapts readily to environmental oxygen tensions, haemoglobins, prepared from normoxic- and hypoxic-accimated eels (Anguilla anguilla) show no adaptive changes in oxygenation properties or in multiplicity. Hypoxic acclimation is, howeveer, accompanied by a strong decrease in red cell nucleoside triphosphates,(More)
Stimulated by the many physiological functions of fish gills this study reports on perfusion studies of gill arches and head preparations from the Atlantic cod, Gadus morhua, with the objective of determining the oxygen requirement of gill tissues in situ. An additional objective was to assess what fraction of the gill tissue O2 consumption is taken up(More)