![Fig. 2. Effects of caffeine on myoplasmic free calcium concentration ([Ca2+]i) in malignant hyperthermia–susceptible (MHS) swine. Simultaneous recording, using double-barreled microelectrodes, of Vm and [Ca2+]iin a MHS fiber before and after caffeine 2 mm was added. In swine, physiologic solution Vm was −81 mV and [Ca2+]iwas 354 nm. The addition of 2 mm induced an elevation of [Ca2+]Ito 1,009 nm, which was associated to muscle fiber shortening. There was no change in resting membrane potential. Measurements of Vm and [Ca2+]ibefore and after caffeine was added to the bath were conducted in same muscle fiber. (Left and right ) The calibration bars for the Ca2+-selective microelectrode and the membrane potential, respectively, are shown.](https://asa2.silverchair-cdn.com/asa2/content_public/journal/anesthesiology/92/6/10.1097_00000542-200006000-00040/2/40ff2.png?Expires=1716446352&Signature=fwk8p65Bc3yQOQBp2qtsCiFGsovBQrGG~kUAin1gUxUXf5ELnbfiuUbkU5vQecSxFQTF0YniuOz1pUr9WE4HPk~cBuC~QIfuCuTaDVO4d4GyXcHycNDSX~-MVxDnlxFwkz7josBGoDB3JDlEdhA-ARaOCtgPUaAE9XEPrjwDxZ5W53K4T~W3UOxn91zSBdhHkiZOgjGmnUVKrKkaHPwyJa3XCaBud3JI0a4r4tv3HWiN1u1affX~SK6oBmLgery1kOotp0Qv968e0k1gIfkxvXsV~Rn9R66v3bZ1QR~aari~8aP7nh0vh-mGtPwvAx-Hq2SkfEyoe94dQ0kQyTuOtA__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
Fig. 2. Effects of caffeine on myoplasmic free calcium concentration ([Ca2+]i) in malignant hyperthermia–susceptible (MHS) swine. Simultaneous recording, using double-barreled microelectrodes, of Vm and [Ca2+]iin a MHS fiber before and after caffeine 2 mm was added. In swine, physiologic solution Vm was −81 mV and [Ca2+]iwas 354 nm. The addition of 2 mm induced an elevation of [Ca2+]Ito 1,009 nm, which was associated to muscle fiber shortening. There was no change in resting membrane potential. Measurements of Vm and [Ca2+]ibefore and after caffeine was added to the bath were conducted in same muscle fiber. (Left and right ) The calibration bars for the Ca2+-selective microelectrode and the membrane potential, respectively, are shown.
