Temperature-dependent pH regulation in stenothermal Antarctic and eurythermal temperate eelpout (Zoarcidae): an in-vivo NMR study

Abstract

Temperature-dependent adjustments of intracellular pH are thought to play a major role in the maintenance of protein function. Comparative studies were carried out in two species from the same ®sh family (Zoarcidae), the stenothermal Antarctic eelpout (Pachycara brachycephalum) and the eurythermal eelpout (Zoarces viviparus), to ®nd out whether pH regulation is modi®ed by temperature in the closely related species and to what extent the respective pattern diers between eurytherms and stenotherms. Previous invasive studies had compared individual animals sampled at various temperatures and suggested that a decrease in intracellular pH (pHi) values occurs at rising temperatures, as predicted by the alpha-stat hypothesis of acidbase regulation. The present study used non-invasive in vivo 31 P-NMR spectroscopy in non-anaesthetized, unrestrained ®sh for long-term online recordings in individual specimens. Control spectra obtained at T=0°C for P. brachycephalum and at 12°C for Z. viviparus indicated low stress conditions, as well as a high stability of energy and acid-base status over time periods longer than 1 week. Temperature changes had no in¯uence on the concentration of high-energy phosphates like phosphocreatine or ATP. Temperature-induced pH changes were monitored continuously in a range between 0 and 6°C for polar, and 12 and 18°C for temperate eelpout. A pHi change of around ±0.015 pH units/°C was observed within both species, in accordance with the alpha-stat hypothesis; however, extrapolation to the same temperature revealed dierent set points of pH regulation in the two species. These ®ndings con®rm that an alphastat pattern of pH regulation can be found in stenothermal Antarctic animals, at set points deviating from an alpha-stat pattern, however, in a between-species comparison.

Correlation of cardiac performance with cellular energetic components in the oxygen-deprived turtle heart

“…In vivo 31 P-NMR spectroscopy parameters were as follows: sweep width, 4,000 Hz; flip angle, 60°(pulse shape, bp32; pulse length, 200 s); TR, 1 s; scans, 512; total acquisition time, 8 min 32 s. 31 P-NMR spectra were processed using TopSpin v1.0 software (BrukerBioSpin MRI, Ettlingen, Germany) and an automatic analyzing routine (written by R.-M. Wittig, Alfred-WegenerInstitute for Marine and Polar Research) to yield integrals of all major peaks within the spectrum (Fig. 1), as these correlate with the amount of substance within the detection volume of the 31 P-NMR coil (9). Briefly, a fit function consisting of a combination of Gaussian and Lorentz line shapes (BrukerBioSpin, Ettlingen, Germany) was adjusted semiautomatically to all signals, resulting in signal integrals.…”

Temperature‐dependent changes in energy metabolism, intracellular pH and blood oxygen tension in the Atlantic cod

“…carpio L. (PCr : Pi ffi 30) and by Bock et al (2001) for eelpouts (PCr : Pi ffi 15). The high PCr : Pi ratio in Atlantic cod results as a consequence of extremely low Pi values.…”

“…For pH i analyses, subsequent spectra were added until the Pi signal could be clearly distinguished from noise and the position of the signal was determined relative to PCr. pH values were calculated and corrected for temperature from chemical shift data as described by Bock et al (2001). The Gibbs' free energy change of ATP hydrolysis (dG/dz) was calculated according to the methodology outlined by Po¨rtner et al (1996).…”

Alkaline biodegradable implants for osteoporotic bone defects—importance of microenvironment pH

“…convention glass pH electrode [20]), gravimetric [21] and spectroscopic (e.g. nuclear magnetic resonance (NMR)-based spectroscopy [22]; near-infrared diffuse reflectance spectroscopy (NIRS) [23]). However, the ordinary bulky glass pH electrode is not suitable for measuring μe-pH, the gravimetric pH detection system has the drawback of a long response time, while NMR cannot be used routinely [19].…”