The Inorganic and Amino Acid Composition of Some Lamellibranch Muscles

Abstract

1. Measurements have been made of the inorganic ion and free amino acid content of a number of lamellibranch muscles. The volumes of extracellular fluid in the muscles have also been determined so that the intracellular concentrations can be calculated. 2. The fast portion of the adductor muscle of Pecten contains about 160 mM. K/kg. fibre water and only 43 mM. Na/kg. fibre water and 34 mM. Cl/kg. fibre water. The potassium and chloride are approximately in a Donnan equilibrium with the potassium and chloride in the blood. 3. In the slow portion of the adductor muscle of Pecten and in the two parts of the adductor and in the byssus retractor of Mytilus, the concentrations of potassium in the fibres are from 150 to 160 mM./kg fibre water, of sodium 73 to 95 mM./kg. fibre water and chloride 94 to 152 mM./kg. fibre water. The potassium and chloride in the fibres are not in a Donnan equilibrium with the potassium and chloride in the blood. 4. The fast and slow fibres of the adductor muscles of Anodonta contain 21 and 17 mM./kg. fibre water of potassium respectively, 5·3 and 7·2 mM./kg. fibre water of sodium, and 2·4 and 5·4 mM./kg. fibre water of chloride. The potassium and chloride in the fibres is not in a Donnan equilibrium with the potassium and chloride in the blood. 5. The fast fibres of Mytilus adductor contain 295 mM./kg. fibre water of free amino acids and 39 mM./kg. fibre water of acid-soluble phosphate compounds. The fast fibres of Anodonta adductor contain only 11 mM./kg. fibre water of amino acids and 19·8 mM./kg. fibre water of phosphate compounds. 6. Mytilus muscles fibres adapt to a reduced blood concentration, partly by an increase in water content and partly by a reduction in the sodium, chloride and free amino acid content. 7. Anodonta muscle fibres adapt to an increased blood concentration, partly by a reduction in the water content and partly by an increased sodium and chloride content. 8. The significance of these results is discussed. It is concluded that the ionic contents of the lamellibranch smooth muscles are consistent with equilibria systems in which the permeability to sodium is significant compared with the permeability to potassium and in which both a sodium and a potassium pump operate.

Relationship Between Ammonia Excretion Rates and Hemolymph Nitrogenous Compounds of a Euryhaline Bivalve During Low Salinity Acclimation ,

“…Therefore, in the whole animal amino acids are released intact from cells into the blood, as Pierce and Greenberg ( 1972 ) have demonstrated with isolated tissue, rather than being degraded intracellularly. In fact, similar changes in blood amino acid concentrations have also been observed in crustaceans (Vincent-Marique and Gilles, 1970;Haberfield, 1971;Gerard and Gilles, 1972), as well as in several polychaete annelids (Clark, 1968) and Mytilus cdnlis, another mussel (Potts, 1958;Bricteux-Gregoire, Duchateau-Bosson, Jeuniaux, and Florkin, 1964). Second, since peak concentrations of ammonia both in the blood and outside the animal follow the elevation of free amino acid concentrations in the blood, the increased production is most likely due to degradation of amino acids by a particular organ of the body following the volume regulation response.…”

CHARACTERISTICS OF INFLUX AND NET FLUX OF AMINO ACIDS INMYTILUS CALIFORNIANUS

“…(Na + ) e is 425 mEq/liter in MBL (Cavanaugh, 1956). Potts (1958) reported that the sodium concentration in the sarcoplasm of several muscle types from M. edulis was approximately 80 mEq/liter. Murakami and Takahashi (1975) found a more or less steady resting potential of about 60 mV (inside negative) in the lateral cells from isolated gills of J\I.…”

Studies of Intracellular pH Regulation in Cardiac Myocytes From the Marine Bivalve Mollusk, Mercenaria campechiensis

“…The calibration solution was identical to MASW except that it contained 290 mA/NaCl, 160 mAl KC1 and nigericin (5 fig/ml). The concentration of K.C1 chosen brackets values for intracellular K 1 as determined in the muscles of marine mollusks (Potts, 1958;Robertson, 1965;Burton, 1983). Cells were allowed to equilibrate with each solution until ratios stabilized (generally <5 min).…”