C

Exopiasmic face

Outside-out patch measures effects of extracellular solutes on channels within isolated patch

Inside-out patch measures effects of intracellular solutes on channels within isolated patch

Outside-out patch measures effects of extracellular solutes on channels within isolated patch

Open Closed 10 ms

Open Closed 10 ms

▲ EXPERIMENTAL FIGURE 7-18 Ion flux through individual Na+ channels can be calculated from patch-clamp tracings.

Two inside-out patches of muscle plasma membrane were clamped at a potential of slightly less than that of the resting membrane potential. The patch electrode contained NaCl. The transient pulses of electric current in picoamperes (pA), recorded as large downward deviations (blue arrows), indicate the opening of a Na+ channel and movement of Na+ ions inward across the membrane. The smaller deviations in current represent background noise. The average current through an open channel is 1.6 pA, or 1.6 X 1CT12 amperes. Since 1 ampere = 1 coulomb (C) of charge per second, this current is equivalent to the movement of about 99CC Na+ ions per channel per millisecond: (1.6 X 10~12 C/s)(10~3 s/ms)(6 X 1023 molecules/mol) ^ 96,500 C/mol. [See F J. Sigworth and E. Neher, 1980, Nature 287:447.]

Microinject mRNA encoding channel protein of interest

Plasma membrane

Plasma membrane

Incubate 24-48 h for synthesis and movement of channel protein to plasma membrane

Measure channelprotein activity by patch-clamping technique

10 Ways To Fight Off Cancer

10 Ways To Fight Off Cancer

Learning About 10 Ways Fight Off Cancer Can Have Amazing Benefits For Your Life The Best Tips On How To Keep This Killer At Bay Discovering that you or a loved one has cancer can be utterly terrifying. All the same, once you comprehend the causes of cancer and learn how to reverse those causes, you or your loved one may have more than a fighting chance of beating out cancer.

Get My Free Ebook


Post a comment