Figure 5. Microfilament disruption reduces the hypotonic stimulation of the active Na⁺ efflux.

A, cytochalasin B (Cyto-B, 5 μm), a depolymeriser of microfilaments, reduced by ∼35 % the rise of the Na⁺ efflux induced by π = 0.5. The dotted curve represents a baseline obtained by fitting a single exponential to the points in π= 1 medium. Mean data from nine identical experiments performed in paired homologous muscles. B, latrunculin B (Lat-B, 10 μm), a microfilament depolymerising agent that is 1–2 orders of magnitude more potent than cytochalasins, reduced the hypotonic response of Na⁺ efflux by ∼72 %. Dotted curve as in A (n = 4 muscle pairs).