The effect of Ca2+, Cd2+ and Ni2+ on detergent-permeabilized vascular smooth muscle from the shark, Squalus acanthias.
We examined the effect of Ca2+, Cd2+, or Ni2+ on vascular smooth muscle intracellular proteins involved in contraction, using rings of detergent-permeabilized aortae from the spiny dogfish, Squalus acanthias. Addition of Ca2+ stimulated contraction of the vascular smooth muscle, and permeabilization by treatment with Triton X-100 increased the sensitivity to Ca2+ nearly 5 log units, demonstrating that this protocol left contractile and regulatory proteins intact. Addition of 1 microM calmodulin did not increase the sensitivity of the rings to Ca2+, suggesting that this preparation is not leaky to this regulatory protein. Neither Cd2+ nor Ni2+ stimulated contraction of permeabilized rings demonstrating that the previously-described contractile action of these heavy metals is not mediated by direct stimulation of intracellular proteins, rather by interaction with sarcolemmal proteins.
Evans
D H
DH
Department of Zoology, University of Florida, Gainesville 32611.
Chipouras
E
E
Toop
T
T
Donald
J A
JA
D000818:Animals; D001011:Aorta; D002104:Cadmium / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D066298:In Vitro Techniques; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D009532:Nickel / Q000494:pharmacology*; D017830:Octoxynol; D012754:Sharks
D002104:Cadmium; D009532:Nickel; D017830:Octoxynol; D002118:Calcium