PubMed · 4428910
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K Borchert, H Wendel, K Trottnow, F Thierbach. 1974-07-19. [Anesthesiological problems in thoracoscopy].. https://pubmed.ncbi.nlm.nih.gov/4428910/
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Midland painted turtles from Michigan were submerged at 3 degrees C in normoxic and anoxic water. In predive, and in turtles submerged for up to 150 days, plasma PO2, PCO2, pH, [Cl-], [Na+], [K+], total Mg, total Ca, lactate, glucose, and osmolality were measured; hematocrit and mass were determined, and plasma [HCO3-] was calculated. Anoxic turtles developed a severe metabolic acidosis, accumulating lactate from a predive value of 4.4 mmol/L to a 150-day value of 185 mmol/L, associated with a fall in pH from 7.983 to 7.189. To buffer lactate increase, total calcium and magnesium rose from 3.7 and 2.6 to 58.9 and 11.8 mmol/L, respectively. Plasma [HCO3-] was titrated from 39.2 to 4.8 mmol/L in anoxic turtles. Turtles in normoxic water had only minor disturbances of their acid-base and ionic statuses, associated with a much smaller increase of lactate to 23 mmol/L; there was a marked increase in hematocrit from 29.1% to 42.1%. We suggest that it is ecologic, rather than phylogenetic, relationships that determine the responses of painted turtles to prolonged submergence associated with hibernation.
Acid-base status influences many aspects of insect biology, including insect distributions in aquatic systems, insect-plant and insect-pathogen interactions, membrane transport phenomena, and the mode of action of pesticides. Acid-base status in the hemolymph and gut lumen of insects is generally well regulated but varies somewhat within individuals owing to effects of temperature, activity, discontinuous ventilation, and diet. The pH of the midgut lumen varies with the phylogeny and feeding ecology. Insect fluids have buffer values similar to those of vertebrates. The respiratory system participates in acid-base homeostasis primarily by regulating the internal carbon dioxide (partial) pressure via changes in spiracular opening and convective ventilation. The epithelia of the renal system and gut participate in hemolymph acid-base regulation by varying acid-base transport in response to organismal acid-base status. Evidence to date suggests that the dominant mechanisms for control of renal acid-base excretion involve hormonal regulation of H+-V-ATPase activity.
Certain parameters above a given intensity of an incremental exercise load are diverging from the linearity of the load and oxygen uptake. This intensity in Watts, speed or percent of the maximal oxygen uptake is called as "anaerobic threshold". The not fully understood events can reflect a relative local oxygen deficiency, levelling off the elimination of lactic acid, consecutive changes in ventilation, levelling off of the stroke volume and/or the macroerg phosphate turnover, uprising of the sympathoadrenal activation, changes in the activation of motor units etc. Empirically the "threshold" has been effectively applied by the performance physiologist and a growing body supports its use in the clinical diagnostics and (cardiac) rehabilitation. Some of the "threshold" parameters (acid-base status, lactic acid level, heart rate deflection) were easily available. Connected to the (spiro)ergometry, "thresholds" offer a valid, objective measure for fitness assessment and for monitoring of the effects of medicaments. It is rational to standardise certain diagnostic parameters to the "threshold" load.