scholarly journals Stimulation of Oxygen Consumption with Fluid Absorption in Insect Recta

1982 ◽  
Vol 101 (1) ◽  
pp. 233-254
Author(s):  
D.F. HOULIHAN ◽  
D. SELL
Keyword(s):  
Oxygen Consumption ◽  
Time Course ◽  
Fluid Injection ◽  
Fluid Absorption ◽  
Fluid Uptake ◽  
Local Osmosis ◽  
Before And After ◽  
Rate Of Oxygen Consumption ◽  
Stimulation Of

The oxygen consumption of excised abdomens of cockroaches and locusts has been measured before and after the injection of fluids into the ligated recta. Fluid injection caused a transient stimulation of oxygen consumption of up to 30% of the resting rate. The extra amount of oxygen consumed is positively correlated with the osmolality of the fluid injected and the amount of fluid absorbed. Parallel experiments were carried out on the time course of fluid uptake; these experiments revealed a correlation first between a rapid increase in fluid absorption and stimulation of oxygen consumption, and secondly between the final resting rate of oxygen consumption and a slower absorption of fluid. Locusts take up fluid at double the rate of cockroaches and have double the stimulation in oxygen consumption following fluid injection. In locusts the increases in oxygen consumption can also be correlated with the net movement of Na+, K+and Cl− from the rectum. The stimulation of oxygen consumption during fluid uptake is discussed in relation to the local osmosis model for fluid uptake.

Studies on Locust Rectum: II. Identification of Specific Ion Transport Processes Regulated by Corpora Cardiaca and Cyclic-AMP

1980 ◽  
Vol 86 (1) ◽  
pp. 225-236
Author(s):  
J. H. SPRING ◽  
J. E. PHILLIPS
Keyword(s):  
Cyclic Amp ◽  
Ion Transport ◽  
Time Course ◽  
Transport Processes ◽  
Electrogenic Transport ◽  
Corpora Cardiaca ◽  
Before And After ◽  
Net Flux ◽  
Unidirectional Fluxes ◽  
Stimulation Of

Please send reprint requests to J. E. Phillips. 1. The unidirectional fluxes of 36Cl− and 22Na+ across short-circuited locust recta bathed in a simple NaCl saline were followed with time. Unidirectional fluxes and net flux of 22Na+ to the haemocoel side all remained constant for at least 4 h and were unaffected by either corpora cardiaca homogenate (CC) or cAMP. 2. Both CC and cAMP stimulated influx and net flux of 36Cl− to the haemocoel side. Over the whole time course of the experiment, i.e. both before and after stimulation, net Cl− flux approximately equalled the shortcircuit current (ISC). 3. Neither CC nor cAMP caused substantial stimulation of ISC or transepithelial electropotential difference (PD) if all Cl− in the bathing saline was replaced by either sulphate or nitrate or acetate. 4. Acetate saline sustains ISC, PD and transepithalial resistance (R) at higher levels than does simple Cl-saline. 5. Experiments with Cl-free, SO4-salines suggest that alternate electrogenic transport processes can be slowly turned on when Cl− is absent, provided a complex saline which contains several organic constituents, or simple acetate saline, is present.

scholarly journals Glycolysis in Neurons, Not Astrocytes, Delays Oxidative Metabolism of Human Visual Cortex during Sustained Checkerboard Stimulation in vivo

2001 ◽  
Vol 21 (12) ◽  
pp. 1384-1392 ◽  
Author(s):  
Albert Gjedde ◽  
Sean Marrett
Keyword(s):  
Oxygen Consumption ◽  
Visual Cortex ◽  
Glucose Metabolism ◽  
Oxidative Metabolism ◽  
Time Course ◽  
Complex Stimulus ◽  
Neuronal Activation ◽  
Positron Emission ◽  
Stimulation Of

The regulation of brain energy metabolism during neuronal activation is poorly understood. Specifically, the extent to which oxidative metabolism rather than glycolysis supplies the additional ATP necessary to sustain neuronal activation is in doubt. A recent hypothesis claims that astrocytes generate lactate with the muscle-type lactate dehydrogenase (LDH) isozyme LD5. Lactate from astrocytes then undergoes oxidation in neurons after reconversion to pyruvate by the LDH subtype LD1. On the basis of this hypothesis, the authors predicted that the time course of an excitatory increase of the oxidative metabolism of brain tissue must depend on the degree to which astrocytes provide neurons with pyruvate in the form of lactate. From the known properties of the LDH subtypes, the authors predicted two time courses for the changes of oxygen consumption in response to neuronal stimulation: one reflecting the properties of the neuronal LDH subtype LD1, and the other reflecting the astrocytic LDH subtype LD5. Measuring oxygen consumption (CMR o2) with positron emission tomography, the authors demonstrated increased CMR o2 during sustained stimulation of visual cortex with a complex stimulus. The CMR o2 increased 20.5% after 3 minutes and 27.5% after 8 minutes of stimulation, consistent with a steady-state oxygen–glucose metabolism ratio of 5.3, which is closest to the index predicted for the LD1 subtype. The index is equal to the oxygen–glucose metabolism ratio of 5.5 calculated at baseline, indicating that pyruvate is converted to lactate in a cellular compartment with an LDH reaction closest to that of LD1, whether at rest or during stimulation of the visual cortex with the current stimulus. The findings are consistent with a claim that neurons increase their oxidative metabolism in parallel with an increase of pyruvate, the latter generated by neuronal rather than astrocytic glycolysis.

Oxygen consumption following exercise in the anesthetized dog

1964 ◽  
Vol 206 (1) ◽  
pp. 51-56 ◽  
Author(s):  
Herbert L. Kayne ◽  
Norman R. Alpert
Keyword(s):  
Oxygen Consumption ◽  
Tetanic Stimulation ◽  
Plasma Lactate ◽  
Hind Limbs ◽  
Before And After ◽  
Lactate And Pyruvate ◽  
Complete Dissociation ◽  
Stimulation Of

Oxygen consumption and plasma lactate and pyruvate were measured in normal, eviscerated, eviscerated-hepatectomized, and eviscerated-hepatectomized-insulin-treated dogs before and after 5 min of mild exercise (direct tetanic stimulation of the muscles of the hind limbs.) The excess consumptions of oxygen during recovery were the same in all four groups; however, lactate and pyruvate removal were markedly impaired in the operated animals. This indicates a complete dissociation between oxygen consumption and metabolite removal during recovery from exercise.

THE ROLE OF LACTATE IN THE STIMULATION OF THE OXYGEN CONSUMPTION OF FROG MUSCLE BY INSULIN

1964 ◽  
Vol 42 (1) ◽  
pp. 139-151 ◽  
Author(s):  
D. R. H. Gourley ◽  
Kenneth C. Fisher
Keyword(s):  
Oxygen Consumption ◽  
Major Effect ◽  
Ringer Solution ◽  
Frog Muscle ◽  
Complete Oxidation ◽  
Rate Of Oxygen Consumption ◽  
Lactate Utilization ◽  
Stimulation Of ◽  
Extra Oxygen

Lactate, citrate, succinate, or acetate added to isolated muscles suspended in Ringer solution in a Warburg flask produced an increase in the rate of oxygen consumption by the muscles. At a given molar concentration of these substances the increase was greatest with lactate and was progressively less with the addenda in the order given. When the concentration of each substance was adjusted so that the rate of oxygen consumption was the same with all of them, the addition of insulin produced an increase in the oxygen uptake which was of the same magnitude in each case. Evidence is presented which suggests that by causing spontaneous activity in the muscle, the acetate, succinate, and citrate may bring about a production of lactate.The extra oxygen consumed upon the addition of lactate could account for the complete oxidation of only a small part of the lactate which actually disappeared in an experiment. By assuming that all of this extra oxygen was used in the complete oxidation of lactate, it was calculated from the total lactate utilization in the presence or absence of insulin that the major effect of insulin was on the fraction of utilized lactate which was oxidized. This conclusion was also suggested by experiments with monoiodoacetate.

Relationship between motility and oxygen consumption of sperm from the cauda epididymides of the rat

1999 ◽  
Vol 11 (2) ◽  
pp. 87 ◽  
Author(s):  
R. N. Murdoch ◽  
R. C. Jones ◽  
V. L. Armstrong ◽  
J. Clulow
Keyword(s):  
Oxygen Consumption ◽  
Respiration Rate ◽  
Sperm Motility ◽  
Dibutyryl Camp ◽  
Epididymal Sperm ◽  
Exogenous Substrate ◽  
Individual Effects ◽  
Rate Of Oxygen Consumption ◽  
Stimulation Of

The oxygen consumption of rat sperm was low (2.7 µL O2 108 sperm–1h–1) in caudal epidi-dymal semen (CES) when stimulation of motility was avoided. The addition of 1 µL of Krebs Ringer phosphate buffer (KRP) to 40 µL of CES (CES : KRP = 40 : 1) did not activate motility, but stimulated oxygen consumption 2-fold. Inclusion of 1–5 mМ glucose, acetate, pyruvate or lactate in the KRP further stimulated respiration rate (up to 4.3-fold) without activating motility, but respiration was reduced when 2- deoxyglucose replaced energy substrates. Inclusion of dibutyryl cAMP (1 mM) activated sperm motility in all samples and stimulated oxygen consumption 2.9-fold. Dilution of CES at the ratio of CES : KRP = 40 : 1000 also activated sperm motility and stimulated respiration rate 2.9-fold. The combined effect of dibutyryl cAMP and glucose in stimulating respiration was greater than their individual effects. However, the response to cAMP or substrates was not altered by incubation in KRP containing either 0 or 0.5 mM Ca2+. It was concluded that the motility and metabolism of rat epididymal sperm are suppressed in vivo. Respiration can be stimulated by a small (1.025-fold) dilution and further stimulated by the inclusion of energy substrate, without activating motility. However, a larger dilution or inclusion of cAMP activated motility and simultaneously stimulated metabolism, with exogenous substrate being required to stimulate respiration to the maximum rate. This suggests that prior to activation, the rate of oxygen consumption and sperm motility are not coupled.

scholarly journals The response to monochromatic light flashes of the oxygen consumption of honeybee drone photoreceptors.

1987 ◽  
Vol 89 (5) ◽  
pp. 791-813 ◽  
Author(s):  
G J Jones ◽  
M Tsacopoulos
Keyword(s):  
Oxygen Consumption ◽  
Time Course ◽  
Monochromatic Light ◽  
Action Spectrum ◽  
Photoreceptor Cells ◽  
Inhibitory Effect ◽  
Experimental Conditions ◽  
Honeybee Drone ◽  
Light Flashes ◽  
Stimulation Of

Local measurements of the fall in oxygen pressure on stimulation of slices of the retina of the honeybee drone by flashes of light were made with oxygen microelectrodes and used to calculate the kinetics of the extra oxygen consumption (delta QO2) induced by each flash. The action spectrum for delta QO2 was obtained from response-intensity curves in response to brief (40 ms) monochromatic light flashes. The action spectrum of receptor potentials was obtained with the same experimental conditions. The two action spectra match closely: they deviate slightly from the photosensitivity spectrum of the drone rhodopsin (R). The deviation is thought to be due to wavelength-dependent light scattering and absorption in the preparation. In these experiments, the visual pigment was first illuminated with orange light, which is known to convert the bistable drone photopigment predominantly to the R state from the metarhodopsin (M) state. When long (300-900 ms) light flashes were used to elicit delta QO2, the responses to different wavelengths could not be matched in time course (as for the short flashes). Flashes producing large R-to-M conversions produced a prolonged delta QO2. The prolongation did not occur after double flashes, which produced both large R-to-M and M-to-R conversions. Similar changes in the length of afterpotentials in the photoreceptor cells and in a long-lasting decrease in photoreceptor intracellular K+ activity were found after long single or double flashes. The results are interpreted to show that the initial event for stimulation by light of metabolism in the drone retina is the same as that for stimulation of electrical responses (i.e., absorption of photons by R). Absorption of photons by M can produce an inhibitory effect on this stimulation.

Evidence for separate sympathetic regulation of fluid absorption and blood flow in the feline jejunum

1984 ◽  
Vol 247 (5) ◽  
pp. G510-G514 ◽  
Author(s):  
H. Sjovall
Keyword(s):  
Splanchnic Nerve ◽  
Transmission Mechanism ◽  
Fluid Absorption ◽  
Jejunal Segment ◽  
Before And After ◽  
Sympathetic Regulation ◽  
The One ◽  
Ganglionic Transmission ◽  
Splanchnic Nerve Stimulation ◽  
Stimulation Of

Splanchnic nerve stimulation (SNS) in cats leads to a jejunal vasoconstriction and to an enhancement of jejunal net fluid absorption. We tested the possibility that the sympathetic fibers to the transporting epithelium might use a ganglionic transmission mechanism different from the one utilized by the jejunal vasoconstrictor nerves. The splanchnic nerves were stimulated before and after a dose of hexamethonium sufficient to entirely block the intestinal vasoconstrictor fibers. However, SNS still increased net fluid absorption in these hexamethonium-treated animals. The hexamethonium-resistant increase in fluid absorption during SNS was a neurogenic effect on the jejunal segment, as it was eliminated by mesenteric denervation and could be reproduced by stimulation of the nerves surrounding the superior mesenteric artery. These data indicate that the rate of jejunal fluid absorption may be regulated by sympathetic fibers functionally distinct from the intestinal vasoconstrictor nerves.

Exercising with and Without Lungs: II. Experimental Elimination of Pulmonary and Buccopharyngeal Gas Exchange in Individual Salamanders (Ambystoma Tigrinum)

1988 ◽  
Vol 138 (1) ◽  
pp. 487-497 ◽  
Author(s):  
MARTIN E. FEDER
Keyword(s):  
Oxygen Consumption ◽  
Gas Exchange ◽  
Ambystoma Tigrinum ◽  
Airway Closure ◽  
Diffusing Capacity ◽  
Oxygen Requirement ◽  
Aerobic Activity ◽  
Before And After ◽  
Rate Of Oxygen Consumption ◽  
Limited Scope

To ascertain whether the presence of lungs per se, or some other physiological feature, might account for the differences in oxygen consumption and stamina previously observed in an interspecific comparison (Full et al. 1988), individual salamanders (Ambystoma tigrinum) were exercised on a treadmill before and after their nares and mouth had been sealed. After airway closure, animals behaved normally and suffered no mortality. Airway closure reduced the routine MO2 (rate of oxygen consumption) by an average of 47% in six of seven individuals. Animals with open airways increased their MO2 2-to 4-fold during locomotion at 11 cm s−1, and did not fatigue in 22 min of exercise at this speed. Animals with closed airways managed only small increases above the routine MO2 during exercise at 11 cm s−1, and none could sustain activity for more than 10 min. Thus, exclusively skin-breathing Ambystoma cannot increase cutaneous gas exchange to compensate for the elimination of pulmonary and buccopharyngeal respiration; locomotor stamina suffers accordingly. Small salamanders can apparently increase cutaneous gas exchange during activity, although large salamanders cannot, because cutaneous diffusing capacity and the resting oxygen requirement approach one another with increasing body size; the skin of large salamanders apparently has a limited scope for aerobic activity.

scholarly journals The relationship between initial creatine phosphate breakdown and recovery oxygen consumption for a single isometric tetanus of the frog sartorius muscle at 20 degrees C.

1979 ◽  
Vol 73 (2) ◽  
pp. 159-174 ◽  
Author(s):  
M Mahler
Keyword(s):  
Oxygen Consumption ◽  
Time Course ◽  
Atp Hydrolysis ◽  
Creatine Phosphate ◽  
Sartorius Muscle ◽  
Exothermic Reactions ◽  
Rate Of Oxygen Consumption ◽  
The Relationship ◽  
Frog Sartorius

A previous paper (Mahler, M. 1978 J. Gen. Physiol. 71:559--580) describes the time-course of the suprabasal rate of oxygen consumption (delta QO2) in the sartorius muscle of R. pipiens after isometric tetani of 0.1--1.0 s at 20 degrees C. To test whether these were the responses to impulse changes in the rate of ATP hydrolysis, we compared the total suprabasal oxygen consumption during recovery (delta[O2]) with the amount of ATP hydrolyzed during a contraction, measured indirectly as the decrease in creatine phosphate (delta[CP]O). If suprabasal ATP hydrolysis during recovery is negligible in comparison with that during contraction, delta[CP]0/delta[O2] should approximate the P:O2 ratio for oxidative metabolism, which has an expected value of 6.1--6.5. We found: formula; see text. We conclude that in this muscle at 20 degrees C: (a) after a tetanus of 0.2--1.0 s, delta QO2(t) can be considered the response to an impulse increase in the rate of ATP hydrolysis; (b) the reversal during recovery of unidentified exothermic reactions occurring during the contraction (Woledge, R. C. 1971. Prog. Biophys. Mol. Biol. 22:39--74) can be coupled to an ATP hydrolysis that is at most a small fraction of delta[CP]0; (c) the pooled mean for delta[CP]0/delta[O2], 6.58 +/- 0.55, sets an experimental lower bound for the P:O2 ratio in vivo.

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