PubMed · 5830098
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A Liermain, R Chevais. 1965. [Practical data on acid-base equilibrium].. https://pubmed.ncbi.nlm.nih.gov/5830098/
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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.
BACKGROUND: Parameters of splanchnic regional perfusion, like intramucosal pH (pHi) and pCO(2) (pCO(2)i), may predict outcome in septic shock patients. Continuous venovenous haemofiltration (CVVH) has been considered beneficial in haemodynamically unstable septic shock patients. In a prospective, randomized, clinical study, we investigated whether CVVH, in comparison to intermittent haemodialysis (IHD), is able to improve splanchnic regional perfusion in critically ill patients. METHODS: Thirty septic shock patients with acute renal failure were randomized to either CVVH (n=20) or IHD (n=10) groups for renal replacement therapy. Patient characteristics at baseline were not different in terms of severity of illness (APACHE II scores), haemodynamics, and pHi/pCO(2)i values. Systemic haemodynamics, oxygen transport variables, and splanchnic regional perfusion parameters were measured at 0.5, 2, 4 and 24 h after initiation of renal replacement therapy. There were no major changes in vasopressor support throughout the 24-h study period. RESULTS: In contrast to IHD, CVVH caused a decrease in heart rate (-3+/-11 vs +9+/-8/min, P<0.01) and an increase in systolic blood pressure (+12+/-1 vs -5+/-17 mmHg, P<0.05) after 2 h. After 24 h, increased systemic vascular resistance was found in the CVVH group in comparison with the IHD group (+312+/-755 vs -29+/-89 dyne/cm(5), P<0.05) and was accompanied by a decrease in cardiac output (-1.54+/-1.4 vs -0.25+/-0.9 l/min, P<0.01). However pHi values remained constant throughout the 24-h study period in both groups and were not different between the groups (CVVH 7.19+/-0.1 vs IHD 7.19+/-0.1, n.s.) as did the pCO(2)i values (CVVH +7+/-17 vs IHD 0+/-15 mmHg, n.s.) and pCO(2) gap values (CVVH +6+/-15 vs IHD +5+/-12 mmHg, n.s.). CONCLUSIONS: Despite different changes of systemic haemodynamics between CVVH and IHD, CVVH did not improve parameters of splanchnic regional perfusion like pHi, pCO(2)i or pCO(2) gap in septic shock patients.
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.