The sodium and potassium content of cardiac and other tissues of the ox

Considerations for quantification of lipids in nerve tissue using matrix-assisted laser desorption/ionization mass spectrometric imaging

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometric imaging is a technique that provides the ability to identify and characterize endogenous and exogenous compounds spatially within tissue with relatively little sample preparation. While it is a proven methodology for qualitative analysis, little has been reported for its utility in quantitative measurements. In the current work, inherent challenges in MALDI quantification are addressed. Signal response is monitored over successive analyses of a single tissue section to minimize error due to variability in the laser, matrix application, and sample inhomogeneity. Methods for the application of an internal standard to tissue sections are evaluated and used to quantify endogenous lipids in nerve tissue. A precision of 5% or less standard error was achieved, illustrating that MALDI imaging offers a reliable means of in situ quantification for microgram-sized samples and requires minimal sample preparation.

Acetylcholine and electrolyte metabolism in the various chambers of the frog and turtle heart

Evidence has accumulated suggesting acetylcholine may he involved in initiation of the heart heat. Acetylcholine and electrolyte metabolism in the various chambers of the heart have been studied. The area of highest intrinsic rhythm (sinus) contained greater amounts of acetylcholine equivalents, true cholinesterase, choline acetylase and sodium; all of these decreasing in amount in areas of lower intrinsie rhythm. It is concluded that intrinsic rhythm may he directly correlated with overall acetylcholine metabolism and sodium content and inversely related to overall energy metabolism and potassium concentration.

Electrolyte content of rat heart atria and ventricles

Extracellular tissue spaces are compared using inulin, sucrose, chloride and sodium in hearts perfused with Ringer-Locke solution by Langendorff's method. Also chloride and sodium spaces are given for unperfused, fresh hearts. From the inulin spaces the intracellular chloride, sodium, potassium and water concentrations in both perfused and unperfused heart chambers have been calculated. Data showing the specificity of the atrium and ventricles of the heart are presented.

[Contents of glycogen, glycolytic activity and contents of metabolites in the atrioventricular system of bovine hearts (author's transl)]

In the atrioventricular system (AVS) consisting of the compact node, the penetrating bundle and the branching bundles of about 250 bovine hearts there were made several studies: 1. In quickly removed and fixed specimens (distal AV-node, penetrating bundle) determination of a metabolic state with respect to glycogen, glucose, lactate, ATP, ADP, AMP, creatinephosphate, total creatine, gluc-6-phosphate, fructose-6-phosphate, fructose-1,6-diphosphate, dihydroxyacetonphosphate and pyruvate. 2. Determination of glycogen contents and glygolytic activity in AVS and its parts for ischemic times up to three hours. 3. The determination of metabolic contents in samples of connective tissue in atrium and ventricle of bovine hearts. The AV-nodes are poor in glycogen comparable with glycogen content of central nervous system and other ganglia. Penetrating bundles of Hiss and branching bundle belong after liver to the glycogen richest parenchyma of animal tissues. Even after ischemia of 3 h only a part of glycogen was recovered as lactate. The greater part of glycogen must be considered as a structural element of Hiss bundle and branching bundles of the ventricles.

Electrolyte distribution in toad sciatic nerve and spinal cord

The distribution of Na+, K+ and water was studied in spinal cord, sciatic nerve and sartorius muscle of the toad, Bufo arenarum (Hensel). Electrolyte assays and sodium washout curves were made. In sartorius muscle, extracellular water was estimated to account for 18.9% of total tissue weight and the intracellular concentrations of Na+ and K+ were 18.4 and 147.9 mEq/kg of intracellular water respectively. In spinal cord extracellular water was 17.2%, intracellular Na+ was 40.6 mEq/kg of water, and intracellular K+ was at a concentration of 134.5 mEq/kg. Interpretation of washout curves in sciatic nerve could not be as simple as in other tissues due to the connective sheath, and therefore electron micrograph measurements had to be made in order to estimate how much of the total tissue weight could be attributed to the sheath. Assuming that it had a water and electrolyte composition similar to that of plasma, the sheath corresponded to 22.3% of the nerves and contained a proportional fraction of Na+ and K+. These calculations left an 'excess' of Na+ and water to be distributed among the remaining components of sciatic nerve. Application of the pyroantimoniate histochemical technique for Na+ determination disclosed a large amount of precipitate among myelin lamellae both in sciatic nerve and in spinal cord. This might explain at least in part the distribution of the 'excess' Na+ in both nervous tissues.

Distribution of potassium, sodium, and chloride in canine Purkinje and ventricular tissues. Relation to cellular potential

Cellular resting and action potentials and total tissue concentrations of K + , Na + , and Cl - were measured in canine myocardial and Purkinje tissues. The results with myocardium were consistent with those of others: the total tissue concentration of K + was greater than that of Na + of Cl - In Purkinje tissue, the total tissue concentration of K + was relatively low, while that of Na + and of Cl - was high. Extracellular space was calculated on the basis of four different assumptions about the intracellular concentration of one of the ions: (1) the intracellular concentrations of Cl - is zero; (2) the electrochemical equilibrium potential of Cl - equals the cellular resting potential; (3) the electrochemical equilibrium potential of K + equals the cellular maximum diastolic potential; (4) the electrochemical equilibrium potential of Na + equals the reversal of the cellular action potential. In the myocardium, the lowest estimate of extracellular space was 14±2%, and the highest was 18±2%. In the Purkinje tissue, the minimum extracellular space: (1) permitting adequate intracellular K + to account for the maximum diastolic potential was 45±3%; (2) consistent with passive distribution of Cl - was 61±4%; (3) yielding low enough intracellular concentration of Na + to account for the reversal of the action potential was 63±10%. These results suggest that in cardiac Purkinje tissue: (1) the extracellular space is unusually large with respect to that of myocardium and skeletal muscle; (2) intracellular activities of ions do not necessarily equal concentrations; or (3) intracellular space is not necessarily a single compartment.

The effects of external sodium and potassium concentration on the membrane potential of atrioventricular fibers of the toad

Intracellular records were made from fibers in the A-V conducting system of isolated toad hearts. The A-V region was perfused with Ringer's solution of various K and Na concentrations. Resting potential in 2.8 mM [K]o was about 60 mv. Over the range 0.28 to 28 mM, resting potential diminished with increasing [K]o. Spontaneous action potentials appeared when [K]o was increased to 11.2 mM, and when resting potential had fallen to about 40 to 50 mv. Changes in [Na]o over the range 22 to 110 mM had a little effect on resting potential, but there was a linear relation between the peak value of the action potential and log [Na]o. Wenckebach periodicity was observed when [Na]o was lowered.

Quantitative analysis of movements of potassium in rabbit auricles

When rabbit auricles are isolated in physiological saline solution at 29 or 37 °C, the influx or efflux of 42 K follows a course which can be described by the sum of two exponential terms. The presence of an initial fast component is more evident in beating than in spontaneously quiescent auricles, but the fast component is not due to beating because it occurs also in auricles in which beating is stopped by carbachol (2 x 10 -6 M). A small loss of potassium occurs in untreated auricles and a larger one under the influence of certain drugs, such as ouabain (10 -5 M) or dinitrophenol (10 -4 M). Several model systems are considered, especially those with three compartments all or partially communicating with each other, both with regard to exchange of tracer and to net changes in the total ionic content of the compartments. The simplest model which describes the observations had 79 ± 2 (S. E.) % of the tissue potassium free to exchange with the medium and the rest exchanging more slowly with the main fraction. In a steady state at 29 °C, in quiescent left auricles 1⋅07 % of the main fraction exchanged with the medium and 0⋅37 % with the slow fraction per minute. The corresponding rates for beating right auricles were 2⋅25 and 0⋅20 % per minute. In the presence of ouabain (10 -5 M) uptake from the medium to the main fraction was reduced to about 40% of the normal rate, with corresponding net loss of potassium. Dinitrophenol reduced or stopped uptake to the slow fraction and also accelerated loss from the main fraction to the medium.

The distribution of Na and K in cat nerves

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