The Action of Adrenaline on the Ionic Content and on Sodium and Potassium Movements in the Smooth Muscle of the Guinea‐pig Taenia Coli

Inhibitory alpha-adrenergic action of phenylephrine in guinea pig taenia caecum

“…Jenkinson and Morton (6, 7) and Biilbring et al (17) observed 42K-efflux increased by a-adrenoceptor stimulant in the K-depolarized taenia . Their observations were confirmed in this study (data not shown).…”

“…Furthermore, smooth muscle stimulants, such as angiotensin II (26,30) Jenkinson and Morton (6, 7) reported that 42K-efflux was increased by a-adrenergic action in the K-depolarized taenia caecum from guinea pig which was not relaxed by the a-adrenoceptor stimulant. Furthermore Bulbring et al (17) reported that epinephrine increased the rate of 42K-efflux in smooth muscle which was completely depolarized by K2SO4 and that this effect was less in muscle partly depolarized by KCl and was smaller in normal solution. It has been clearly demonstrated in the present study that 42K-efflux in the normal undepolarized smooth muscle is also increased by the a-adrenoceptor stimulant.…”

Effects of norepinephine, calcium, and rate of discharge on 42K movements in canine cardiac Purkinje fibers.

“…If the Purkinje fibers were to be kept quiescent or driven at a very slow rate during the experiment, the driving rate was halved at the beginning of the last hour of the loading period and reduced during the last 30 minutes of the loading period to the rate used subsequently. The stimulation rate during the 42 K load and the duration of the loading period were selected in view of the fact that the radioactivity of Purkinje fibers stimulated at 60/min reaches equilibrium in 140 ± 9.5 minutes. 5 Therefore, after a total of approximately 4 hours, the preparations should have been in equilibrium as far as potassium, active and inactive, is concerned.…”

“…The stimulation was continued at the same rate for about 210 minutes while the strand was perfused in radioactive solution (loading period). The radioactive Tyrode's solution contained 42 K (chemical form KG) obtained from Iso/Serve (Cambridge Nuclear Co.) and was perfused by means of a peristaltic pump (LKB Varioperpex Pump 12000) at a rate of 0.76 ml/ min. About 30 minutes before the end of the loading period, the rate of stimulation was reduced to the value to be used in the remainder of the experiment.…”

“…5 - 6 In a series of five control experiments from this laboratory, 6 Purkinje fiber preparations were loaded with radioactive potassium to equilibrium, and then six VOL. 42 uptake periods were carried out in succession in the absence of test procedures. The first uptake was equated to 100, and the following five uptakes were expressed as a percentage with respect to the first.…”