Expression of cardiac sarcolemmal Na sup + -Ca sup 2+ exchange activity in Xenopus laevis oocytes

Journal Article · Thu Dec 01 00:00:00 EST 1988 · American Journal of Physiology; (USA)

OSTI ID:6252550

Longoni, S; Coady, M J; Ikeda, T; Philipson, K D ^[1]

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1. Univ. of California, Los Angeles (USA)

Injection of Xenopus laevis oocytes with rabbit heart poly(A){sup +}RNA results in expression of Na{sup +} inside (Na{sub i}{sup +})-dependent Ca{sup 2+} uptake activity. The activity was measured by first loading the oocytes with Na{sup +} using nystatin and then incubating the oocytes in K{sup +} or Na{sup +} medium containing {sup 45}Ca. The expressed Na{sup +} gradient-dependent Ca{sup 2+} uptake was five to eight times that observed with water-injected oocytes or with poly(A){sup +}RNA-injected oocytes for which the Na{sup +} load step had been omitted. Induced activity was related to the amount of RNA injected and was insensitive to nifedipine. Fractionation of the poly(A){sup +}RNA on a sucrose gradient determined that the active message had a size range between 3 and 8 kb. The properties of the Na{sup +} gradient-dependent Ca{sup 2+} uptake indicated that Na{sup +}-Ca{sup 2+} exchange activity had been expressed in X. laevis oocytes. The result may be useful for cloning and identifying the molecular component responsible for Na{sup +}-Ca{sup 2+} exchange.

• OSTI ID: 6252550
• Journal Information: American Journal of Physiology; (USA), Vol. 255:6; ISSN 0002-9513
• Country of Publication: United States
• Language: English

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ISOMERIC TRANSITION ISOTOPES
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ORGANIC COMPOUNDS
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551001* - Physiological Systems- Tracer Techniques