Intracellular free magnesium concentration in the taenia isolated from guinea-pig caecum.
The free [Mg]i in the guinea-pig taenia was estimated to be about 300 microM. The [Mg]i remained constant by simple removal of Ca, but reduced by removal of both Ca and Mg, reaching about 8 microM in 100 min. This recovered on Mg readmission. No clear recovery was observed in Na-free (K-substitute) solution containing 2.4mM Ca. Carbachol response was reversibly inhibited when [Mg]i decreased to less than 1/10 of the control. In K-free solution [Mg]i gradually increased to more than 500 microM in 100 min in the absence of Ca, but not in the presence of Ca. A Na-Mg exchange process seems to be playing an important role, in addition to a low permeability of the membrane to Mg, in the regulation of [Mg]i.
Nakayama
S
S
Department of Physiology, School of Medicine, Nagoya University, Japan.
Tomita
T
T
D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D006168:Guinea Pigs; D007420:Intestine, Large; D008274:Magnesium / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology
D002217:Carbachol; D008274:Magnesium