A correlation between the activity of divalent cation activated adenosine triphosphatase in the cell membrane and low salinity tolerance of the ribbed mussel,Modiolus demissus demissus

✍ Scribed by Watts, John A. ;Pierce, Sidney K.

• Publisher: John Wiley and Sons
• Year: 1978
• Tongue: English
• Weight: 581 KB
• Volume: 204
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1402040106

✦ Synopsis

A comparison was made between the bound divalent cation stimulated adenosine triphosphatase (ATPase) activity of the cell membrane and the regulation of free amino-acid (FAA) permeability in the myocardium of the bivalve (Modiolus demissus) during isosmotic and hypoosmotic stress. The FAA efflux induced by isosmotic, divalent cation free, artificial sea water (ASW) was reduced by Ca", Mg'+, Mn2+ and Coz+ at concentrations non-lethal to the intact heart. However, the order of effectiveness in reducing the efflux was not the same as the effectiveness of the divalent cations on the stimulation of ATPase activity. In addition, ATPase activity with the concentrations of Ca2+ and Mg2+ in full strength ASW or in 50% ASW was inhibited by Co2+ and stimulated by Mn". Under isosmotic conditions, modification of ATPase activity by Co2+ or Mn2+ did not alter FAA permeability. However, during hypoosmotic stress, the recovery of normal FAA permeability correlated with divalent cation activated ATPase activity; increased enzyme activity in the presence of Mn" was coincident with a decreased FAA efflux and decreased enzyme activity in the presence of Co" accompanied a n increased FAA efflux.

Therefore, the recovery of normal FAA permeability during a hypoosmotic stress is correlated with divalent ATPase activity. During isosmotic conditions, FAA permeability may be controlled by divalent cation binding.