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We measured the spin-lattice relaxation times (T1) of water protons and intermolecular cross-relaxation times (T(IS)) from irradiated protein protons (f2-irradiation at 1.95 or -4.00 ppm) of rabbit normal and monoiodoacetate-induced degenerated knee articular cartilages to observed water protons. The mean values of T1 (T1) for control and degenerated rabbit knee cartilages were 1.87+/-0.15 (mean+/-SD, n=29) and 1.82+/-0.13 s (n=34), respectively. The mean values of water content (W(H2O)) for control and degenerated rabbit knee cartilages were 82.9+/-2.09 (n=26) and 83.1+/-2.57% (n=28), respectively. These values were not statistically different from each other. However, the mean values of T(IS) (T(IS)) for normal knee articular cartilage were significantly different from those for degenerated cartilage: (normal), T(IS) (f2=1.95 ppm)=2.46+/-0.62 s (n=28), T(IS) (f2=-4.00 ppm)=4.25+/-1.26 s (n=26); (degenerated), T(IS) (f2=1.95 ppm)=1.99+/-0.76s (n=34), T(IS) (f2=-4.00 ppm)=3.33+/-0.76 s (n=31). Obtained results may be attributed to the reported switchover from type II to type I collagen syntheses in osteoarthritic cartilage, resulting in broad collagen fibers. This specificity of cross-relaxation effect may prove useful in the noninvasive and pathophysiological evaluation of cartilage tissues in vivo.

Phosphorus nuclear magnetic resonance (31P NMR) spectroscopy was used to study energy supply for protein secretion in the isolated perfused rat pancreas. Stimulation with cholecystokinin (CCK-8) increased fluid secretion and protein output. With 10pM of CCK-8, the tissue contents of ATP, inorganic phosphate (Pi), and creatine phosphate (PCr) remained unchanged. With 100pM of CCK-8, which induced the maximum response in fluid secretion and protein output, Pi increased slightly, ATP and PCr remained almost unchanged. A high dose of CCK-8 (1 nM) suppressed the fluid and protein secretory rates, decreased ATP, and increased Pi significantly, but PCr showed a tendency of increase. Significant changes in ATP and Pi occurred on withdrawal of CCK-8 (1 nM), suggesting activation of ATP hydrolysis for recovery from secretory suppression. During stimulation with 0.1, 0.3, and 3.0 microM of acetylcholine, the similar dose-dependent response was observed in the secretion and the phosphorus metabolism. The present study demonstrated that cytosolic energy metabolism for secretory responses in the pancreas is low and the Lohmann reaction showed less contribution than in the salivary gland. The findings suggest that the energy supply for protein secretion may be cytosolic diffusion of ATP and that the Lohmann reaction system may contribute to synthesis and storing of secretory protein at resting state.

Aerobic recovery after a 60-sec tetanus of skeletal muscle of frog was studied using the in vivo 31P-NMR method with a topical magnetic resonance spectrometer (TMR) at 17 degrees C. Creatine phosphate recovered with a time constant of about 25 min-1. Sugar phosphates increased by the Pasteur effect, and saturated at about 4.5 mmol/kg muscle. The high level of the sugar phosphates was sustained during the following 60 min.

The present study was undertaken to measure tissue contents of Na, Li, and Cl non-invasively in the isolated perfused organ by nuclear magnetic resonance (NMR) using a broadband tunable probe. The NMR signals of 23Na, 7Li, and 35Cl from the isolated perfused rat mandibular gland were collected continuously and each spectrum was obtained for every 15 or 20 s. The Na concentration in the perfusate was varied by replacement with Li, and the resulting changes were monitored by measuring the signal intensities of the electrolytes. The time constant for Na exchange was slower following complete removal of extracellular Na than following its half replacement, suggesting that the Na extrusion by Na+/K+ ATPase was reduced by lowering the extracellular Na level. The time constant for Li exchange was slower than that for Na exchange. The level of Cl was nearly constant during experiment, except for a very slow increase in Cl, possibly resulting from increasing edema and/or intracellular Li storage.

Phosphorus nuclear magnetic resonance (31P NMR) was used to study energy metabolism in the rat mandibular gland. The gland was isolated, perfused arterially and set in the NMR tube. At rest, 7 resonance peaks were observed and 6 peaks identified from low field as: 1) sugar phosphates (SP) and nucleotide monophosphate (NMP), 2) inorganic phosphate (Pi), 3) creatine phosphate (PCr), 4) gamma-nucleotide triphosphate (NTP) and beta-nucleotide diphosphate (NDP), 5) alpha-NTP, alpha-NDP, NAD+, and NADH, 6) an unknown peak, and 7) beta-NTP. From the results of high performance liquid chromatography (HPLC), NTP consisted mainly of ATP and GTP, and UTP was not detected. The tissue contents of ATP and GTP in the perfused gland were determined by HPLC as 1.86 +/- 0.03 and 0.37 +/- 0.01 mmol/kg wet tissue (S.E., n = 5). From 31P NMR and HPLC data, the tissue levels of creatine phosphate, ADP, and sugar phosphates were estimated as 3.3, 0.4, and 4.2 mmol/kg wet tissue, respectively. The cessation of perfusion decreased the tissue levels of PCr and ATP and increased those of Pi and SP. On the other hand, administration of acetylcholine (1 microM), which is an optimal dose for secretion, decreased PCr and increased Pi but did not change SP. The ATP was unchanged initially and slowly decreased to the lower level during sustained secretion. These findings suggest that a sustained secretion requires more energy from ATP hydrolysis rather than initial secretion.

The 31P-NMR technique was used for the monitoring of intracellular pH and studying its heterogeneity in the femoral biceps muscle of Rana catesbiana under anaerobic conditions. The value of intracellular pH of fresh muscle calculated from the chemical shift of intracellular inorganic phosphate (P1) was 7.3 on average and the line width of P1 was about 0.2 ppm. As the line width determined by the relaxation mechanism was 0.099 ppm, the P1 signal in fresh muscle was concluded to consist of overlapped narrow components, which indicated the heterogeneity of muscular pH (about 0.2 pH unit). Living muscle showed gradual acidification due to glycolysis and the decrease in heterogeneity. When glycolysis was suppressed by iodoacetic acid, slight alkalization due to the breakdown of creatine phosphate was observed. When the Lohmann reaction was suppressed by 2, 4-dinitro-1-fluorobenzene, rapid acidification accompanied by the appearance of a new acidic component was observed with the onset of ATP decrease. This new component was not detected in the muscle pretreated with glycerol to disrupt the transverse tubules. Therefore, it is likely that this new acidic component originates in the intracellular compartment, and not in the cellular difference.

The diffusivities of creatine phosphate and ATP were measured in an aqueous solution by pulsed field gradient 31P NMR. The diffusion coefficient of creatine phosphate was 1.4 times larger than that of ATP, suggesting the advantage of creatine phosphate in the energy transport in muscle cells.

The relationship between the hematocrit value and the absolute value of impedance of whole blood was analyzed. The results indicated that the hematocrit value was linearly proportional to the logarithm of the impedance of whole blood over the range of hematocrit values of 10 to 60% with a correlation coefficient of 0.995. The circuit used for detection of the impedance of whole blood was described. It required no adjustments during measurements and had a wide linear range. The sources of error during continuous measurements were the rate of blood flow through the sensor cell, the temperature of the blood, and the concentrations of plasma proteins and ions. Accordingly, the flow and temperature of blood were kept constant during measurements. Changes in the concentrations of plasma proteins and ions within physiological ranges caused errors of +/- 2.0%. Typical results of continuous measurements were presented, showing that the hematocrit values obtained by this method agreed well with those obtained by the conventional methods from the packed cell volume. An advantage of this method over the conventional methods was that it could follow rapid and transient changes in the hematocrit.

The topical magnetic resonance (TMR) was used to study the phosphorous metabolism of a dog's submandibular gland during acetylcholine stimulation. The experiments were carried out under two conditions. One was a normal blood supply (in vivo) and the other was vascular perfusion with the artificial perfusate (in vitro). The levels of phosphorous compounds in the gland were obtained for 31P-NMR spectra of the TMR. The saliva was secreted in the both conditions, though the salivary flow under the in vivo condition was higher than in vitro. During salivary secretion, only the levels of creatine phosphate decreased under in vivo condition, while the levels of creatine phosphate and ATP decreased and the levels of inorganic phosphate increased in in vitro cases. It was concluded that the decrement of creatine phosphate during the salivary secretion indicates the acceleration of the energy metabolism in the submandibular gland.

The dependency of fluid secretion on extracellular Na+ and the levels of phosphorus compounds were studied in the perfused canine mandibular gland (using 31P-NMR). During control perfusion, the resting levels of creatine phosphate (CP) and ATP were 0.62 +/- 0.05 mmol . kg-1 gland and 0.42 +/- 0.04 mmol . kg-1 (mean +/- S.E., n = 9), respectively. Acetylcholine (Ach; 1 mumol . l-1 for 3 min) induced a salivary secretion and decreased the CP level. When Na+ in the perfusate was completely replaced with Li+, Ach induced only a minimal salivary secretion and no change in the ATP and CP levels. Restitution of Na+ to the perfusion, even without added Ach, caused a decrease in ATP and CP, and a small increase in salivary secretion. These results suggest that the activity of Na+/K+ ATPase is increased inversely via a rise of the intracellular Na+ concentration and that the salivary secretion is induced not only by added secretagogues but by an increase in the Na+ entry without added secretagogues.

Sequential metabolic changes in rat brain were monitored by in vivo measurements of 31P NMR spectra using a topical magnetic resonance (TMR) spectrometer, during the course of experimentally induced cerebral infarction and also during recovery produced by restoration of circulation. The experimental cerebral infarction was rendered by a slightly modified version of the method of Pulsinelli and Brierley (1979). The bilateral coagulation of the vertebral arteries at the level of alar foramina of the first cervical vertebra (preinfarction) did not show any change in NMR spectrum, but the subsequent bilateral ligation of internal carotid arteries produced a decrease in the peaks of ATP and phosphocreatine and a concomitant increase in the peak of inorganic phosphate within a few minutes. Intracellular pH, calculated from the chemical shift of inorganic phosphate, declined. These changes became maximal at approximately 30 min after the infarction. Reinstatement of blood flow to the cerebrum, produced by untying the ligature of internal carotid arteries, resulted in an immediate restoration of the peaks of ATP and phosphocreatine, which was followed by a reduction in the peak of inorganic phosphate within a few minutes. The spectrum recovered to its preinfarction pattern about 30 min after the restoration of the circulation. These experiments demonstrate that phosphorus compounds change very rapidly during infarction, and that these changes were reversible at least during a 30 min period.