Mn++ prevents calcium uptake during potassium-induced contraction in rabbit aortic strips while maintaining contraction, suggesting a complex role in vascular smooth muscle excitation-contraction coupling.
Mn++ effects in rabbit aorta suggest Ca-contraction dissociation; leaves open relevance to human vascular physiology or therapy.
Pretreatment with Mn ++ at 5 and 1 mM for 30 min prevented the increased 45 Ca uptake of rabbit aortic strip observed during the potassium-induced contraction (40 mM) without significantly reducing the magnitude of the contraction and decreased 45 Ca content of unstimulated muscle. Addition of Mn ++ was found to restore the contractile response to potassium after this had been lost in Ca-free media.
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Shoji Shibata (1969) studied this question.
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