The Extracellular Space of Voluntary Muscle Tissues

Abstract

The volume occupied by the extracellular space has been investigated in six types of voluntary muscles: sartorius (frog), semitendinosus (frog), tibialis anticus longus (frog), iliofibularis (frog), rectus abdominis (frog), and diaphragm (rat). With the aid of four types of probe material, three of which are conventionally employed (inulin, sorbitol, sucrose) and one of which is newly introduced (poly-L-glutamate), and a different experimental method, we have demonstrated that the "true" extracellular space of frog sartorius, semitendinosus, tibialis anticus longus, and iliofibularis muscle and of rat diaphragm muscle is equal to, or probably less than, 8-9 % (v/w) of the tissue. The frog rectus muscle shows a somewhat higher ceiling value of 14 %.Living tissue consists of cells and "extracellular space." A precise knowledge of the percentage of extracellular space is essential if one is to obtain meaningful values for the concentrations of solutes or water within the cell. In the case of solutes like Na+ ion and glucose, which are usually found at lower concentrations within the cell than in the extracellular fluid, an erroneous value for the extracellular space may lead to the conclusion that these solutes are altogether absent in the cell, while in truth they are present in sizable concentrations (or vice versa). Yet published values for the extracellular space vary widely. Thus, for frog sartorius muscle the proportion of extracellular space given in the literature varies from 13% of the tissue (1-4) to as high as 35% (5-9). With this degree of uncertainty, meaningful interpretation of quantitative data on "glucose transport" or "sodium transport" in muscle tissues, as examples, is virtually impossible. Such problems are of fundamental importance in understanding the behavior of the living cell.In this communication we present results of investigations of the extracellular space of several types of voluntary muscles of amphibian and mammalian origin. Using new techniques, we have found the extracellular spaces of these tissues to be surprisingly low and constant.

Cable parameters, sodium, potassium, chloride, and water content, and potassium efflux in isolated external intercostal muscle of normal volunteers and patients with myotonia congenita

“…In cardiac muscle, each of these substances is excluded from the intracellular space that is important to electrophysiological function (28). In isolated frog sartorius muscles, mannitol gives values of extracellular volume in close agreement with those predicted from physiochemical considerations (29). Yet variation in the magnitude of measured extracellular volume occurs (30).…”

“…METHODS Normal volunteers. Our normals are 13 males aged [21][22][23][24][25][26][27][28][29][30][31][32][33] The biopsy was placed in a thermos bottle containing previously gassed (95% 02, 5% C02) physiological salt solution at a temperature of from 35 to 38°C, for transportation to the laboratory. Each biopsy was dissected, as previously described (1), so that one or more preparations were used for electrophysiological studies and two to seven preparations for measurement of ion content, ion flux, or extracellular space.…”

Muscle Na + channelopathies

“…More than half of the signal is due to intracellular 23 Na if the partial volume of the extracellular compartment is not greater than 7%. 12 Since the extracellular space of skeletal muscle is less than 8% 27 including the transverse tubular system that is 0.32% of the fiber volume, 28 this prerequisite is fulfilled for normal muscle. Vacuoles, the results of a substantial proliferation of the transverse tubular system, 29 were absent in the patients who underwent a muscle biopsy.…”

Permeation and distribution of deuterated and triated water in smooth and striated muscle

“…Undoubtedly the method of removing surface fluid from the muscle will affect the results, and, as surface fluid was removed in the immersion weighing experiments by draining rather than by blotting, it is not surprising that the value of extracellular space in striated muscle given by these experiments is somewhat higher than most of the reported values (Boyle et al 1941;Ling & Kromash, 1967;Hill, 1965). However, it is also conceivable that stagnant layers on the surface of the muscle during the exchange of HDO could have contributed to the effective volume extracellular fluid associated with the muscle.…”