Laser flash photolysis of diazo-2, a caged calcium chelator: The relationship between the extent and rate of smooth muscle relaxation

Relaxations brought about by laser flash photolysis of diazo-2, a caged calcium chelator, were recorded in the anterior byssus retractor muscle (ABRM) of Mytilus edulis (a molluscan “catch” muscle). The relaxation rate was characterized by half-time (T 1/2 ) and one-fifth-time (T 1/5 ) . We show tha...

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Bibliographic Details
Published in:Journal of laser applications 2009-02, Vol.21 (1), p.32-38
Main Authors: Pelc, R., Ishii, N., Ashley, C. C.
Format: Article
Language:English
Subjects:
caged calcium chelator
catch
diazo-2
laser flash photolysis
latch and smooth muscle
relaxation rate
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Summary:Relaxations brought about by laser flash photolysis of diazo-2, a caged calcium chelator, were recorded in the anterior byssus retractor muscle (ABRM) of Mytilus edulis (a molluscan “catch” muscle). The relaxation rate was characterized by half-time (T 1/2 ) and one-fifth-time (T 1/5 ) . We show that, unlike, e.g., in the mammalian cardiac muscle, the relaxation rate increases with the extent of relaxation (the latter being expressed as a percentage of an immediately preceding activation by Ca 2+ ), in a manner similar to the Ca 2+ activation process, as shown in other muscles [Lea and Ashley, J. Physiol. (Lond.) 427, 435–453 (1990); Saeki et al., J. Mol. Cell. Cardiol. 36, 371–380 (2004)]. This increase (i.e., decrease in T 1/2 and T 1/5 ) levels off at extent of relaxation ≃50% . The present paper highlights the need to take into account the differences in the extent of smooth muscle (especially the catch or “latch” type) relaxation. The data may be used in modeling the mechanism underlying the calcium-dependent (phasic) smooth muscle relaxations.
ISSN:1042-346X
1938-1387
DOI:10.2351/1.3071377