Sodium and potassium content of the smooth muscle of the guinea‐pig taenia coli at different temperatures and tensions

Abstract

Alterations in temperature and tension change the electrical and mechanical activity of the smooth muscle of the guinea-pig taenia coli (Biilbring, 1955; Axelsson & Builbring, 1961), and it was therefore of interest to examine the influence of these factors on the sodium and potassium content of the tissue. Some changes in the distribution of these ions due to variations of temperature and tension have been reported previously. The immediate consequence of stretching the taenia coil was studied by Born & Biilbring (1956) who found an increased rate of loss of potassium, and a similar observation was made by Ikeda, Hayama, Chujyo & Hoshi (1958) in the smooth muscle of the intestinal wall. Cooling uterine smooth muscle was shown by Daniel & Robinson (1960) to decrease the potassium and increase the sodium content of the tissue. Similar changes were observed by Goodford & Hermansen (1961) when taeniae col were dissected and placed in an unoxygenated Ringer's saline solution at room temperature; they were largely reversed when the tissue was transferred to oxygenated Krebs's solution at 350 C.In the present work the effect has been studied of three different temperatures and a range of tensions on the total sodium and potassium content of the guinea-pig taenia coli, the rate of uptake of radioactive sodium and potassium ions, and the ratio of cell surface area to cell volume. METHODSThe procedures used were essentially those described by Goodford & Hermansen (1961). In each experiment 6-12 similar guinea-pigs were used, from each of which 7-10 pieces of taenia coli were dissected as quickly as possible. Each muscle was attached with two loops of cotton to a specially constructed 'spring balance', and was immersed in modified Krebs's solution under conditions specified in the description of results. During the first hour the tension was readjusted from time to time until it became steady at the desired value, and the pieces of muscle were then transferred to a solution containing either radioactive sodium or radioactive potassium. The composition of the solution was mm: Na+ 137, K+ 5.9, Mg2 1-2, Ca2+ 2-5, Cl-134, H2PO 1-2, HCO-15-5, D( + )-glucose 11-5, gassed with 97% O9+ 3 % CO2. It was prepared from isotonic stock solutions as described by Krebs (1950), with * 1851 Senior Student.

The Effects of Temperature and Some Drugs on the Ionic Movements in the Smooth Muscle of Guinea-pig Taenia Coli

“…Several reports have been made of this problem (Daniel,21) Daniel & Robinson22), Kao23), Goodford et al8,9)), but much discrepancy found in these results indicating …”

An estimate of sodium/potassium pump activity and the number of pump sites in the smooth muscle of the guinea‐pig taenia coli, using 3[H]ouabain

“…Freeman- Narrod & Goodford (1962) have calculated that the volume to surface area ratio in the taenia coli is 1-5 /im. If one assumes an extracellular space of 40 % (Brading & Jones, 1969), then each milligram of fresh tissue will have a membrane area of 4 cm2 (this can be compared with the mammalian C fibres which have a surface area of 6 cm2/mg, Keynes & Ritchie, 1965 (Lindowne & Ritchie, 1970).…”

“…The published data available, which result in the figure of 1-5 ,tm (Freeman-Narrod & Goodford, 1962) were obtained from measurements using light microscopy, where the small unevennesses of the surface area are hard to measure.…”

The distribution of ions in the smooth muscle of the guinea‐pig taenia coli

“…This is slowed or abolished at low temperatures and is not resumed at once when the temperature is raised again (Axelsson & Btilbring, 1961) so that there is a period after warming when the taenia is quiescent at 350 C. At this time the muscle sodium content falls and the potassium content rises (Freeman-Narrod & Goodford, 1962), and these changes after warming have now been investigated further. Some of the present observations have already been communicated to the Physiological Society (Buck & Goodford, 1965).…”