The Initiation of Spike Potential in Barnacle Muscle Fibers under Low Intracellular Ca++
نویسندگان
چکیده
Electrical properties of the muscle fiber membrane were studied in the barnacle, Balanus nubilus Darw. by using intracellular electrode techniques. A depolarization of the membrane does not usually produce an all-or-none spike potential in the normal muscle fiber even though a mechanical response is elicited. The intracellular injection of Ca(++)-binding agents (K(2)SO(4) and K salt of EDTA solution, K(3) citrate solution, etc.) renders the fiber capable of initiating all-or-none spikes. The overshoot of such a spike potential increases with increasing external Ca concentration, the increment for a tenfold increase in Ca concentration being about 29 mv. The threshold membrane potential for the spike and also for the K conductance increase shifts to more positive membrane potentials with increasing [Ca(++)](out). The removal of Na ions from the external medium does not change the configuration of the spike potential. In the absence of Ca(++) in the external medium, the spike potential is restored by Ba(++) and Sr(++) but not by Mg(++). The overshoot of the spike potential increases with increasing [Ba(++)](out) or [Sr(++)](out). The Ca influx through the membrane of the fiber treated with K(2)SO(4) and EDTA was examined with Ca(45). The influx was 14 pmol per sec. per cm(2) for the resting membrane and 35 to 85 pmol per cm(2) for one spike. From these results it is concluded that the spike potential of the barnacle muscle fiber results from the permeability increase of the membrane to Ca(++) (Ba(++) or Sr(++)).
منابع مشابه
The Initiation of Spike Potential in Barnacle Muscle Fibers under Low Intracellular Ca + SUSUMU HAGIWARA and KEN - ICHI NAKA
Electrical properties of the muscle fiber membrane were studied in the barnacle, Balanus nubilus Darw. by using intracellular electrode techniques. A depolarization of the membrane does not usually produce an all-ornone spike potential in the normal muscle fiber even though a mechanical response is elicited. The intracellular injection of Ca++-binding agents (K 2SO4 and K salt of EDTA solution,...
متن کاملSurface Density of Calcium Ions and Calcium Spikes in the Barnacle Muscle Fiber Membrane
The effects of various divalent cations in the external solution upon the Ca spike of the barnacle muscle fiber membrane were studied using intracellular recording and polarizing techniques. Analysis of the maximum rate of rise of the spike potential indicates that different species of divalent cations bind the same membrane sites competitively with different dissociation constants. The oversho...
متن کاملBarnacle Muscle Fiber Membrane
The effects of various divalent cations in the external solution upon the Ca spike of the barnacle muscle fiber membrane were studied using intracellular recording and polarizing techniques. Analysis of the maximum rate of rise of the spike potential indicates that different species of divalent cations bind the same membrane sites competitively with different dissociation constants. The oversho...
متن کاملDifferences in Examined by Procaine, and Na and Ca Spikes As Application of Tetrodotoxin, Manganese Ions
The effects of tetrodotoxin, procaine, and manganese ions were examined on the Ca spike of the barnacle muscle fiber injected with Cabinding agent as well as on the action potential of the ventricular muscle fiber of the frog heart. Although tetrodotoxin and procaine very effectively suppress the "Na spike" of other tissues, no suppressing effects are found on "Ca spike" of the barnacle fiber, ...
متن کاملEffects of the Intracellular Ca Ion Concentration upon the Excitability of the Muscle Fiber Membrane of a Barnacle
The membrane excitability and contraction were examined in single barnacle muscle fibers with different internal Ca(++) concentrations by using buffer solutions made up with EGTA and Ca-gluconate in various proportions. During the passage of dc currents the membrane shows all-or-none spike potentials for internal Ca(++) concentrations below about 8 x 10(-8)M, oscillatory potential changes in th...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- The Journal of General Physiology
دوره 48 شماره
صفحات -
تاریخ انتشار 1964