Fig. 7. Typical results of the mechanical test on the dermis in normal artificial seawater (nASW). (A) Effect of elevated K⁺ (100 mmol l^–1) on the stiffness of the dermis. This sample showed a slight decrease in stiffness after the start of the mechanical test. Elevated K⁺ concentration (double-headed arrow) caused an increase in stiffness. (B) Effect of H-tensilin (3 µg ml^–1) on the stiffness of the dermis. A transient increase in stiffness was observed in the first 10 min after the onset of the mechanical test. The application of H-tensilin (single arrow) did not induce stiffening, whereas the subsequent application of ASW with an elevated K⁺ concentration (double-headed arrow) caused marked stiffening.