Heat induced HSP20 phosphorylation without increased cyclic nucleotide levels in swine carotid media.
BACKGROUND
Heat pretreatment of swine carotid artery has been shown to increase ser16-heat shock protein 20 (HSP20) phosphorylation and suppress force, i.e., reduce force with only minimal reduction in ser19-myosin regulatory light chain (MRLC) phosphorylation.


RESULTS
We further investigated this response in intact histamine stimulated swine carotid artery rings. There was a heat threshold such that increased ser16-HSP20 phosphorylation and force suppression were observed between 43 degrees C and 46 degrees C. The increased ser16-HSP20 phosphorylation persisted up to 16 hours after 44.5 degrees C heat treatment. Pretreatment of swine carotid media at 44.5 degrees C increased ser16-HSP20 phosphorylation without increases in [cAMP] or [cGMP], suggesting an alternate mechanism, perhaps phosphatase inhibition, for the increase in ser16-HSP20 phosphorylation. Heat pretreatment at 47.5 degrees C reduced force by decreasing MRLC phosphorylation rather than by large increases in ser16-HSP20 phosphorylation. HSP20 phosphorylation at the putative PKC site did not change with any treatment.


CONCLUSIONS
These results demonstrate that multiple mechanisms can induce force suppression that is correlated with ser16-HSP20 phosphorylation: 1) nitrovasodilators via cGMP, 2) forskolin via cAMP, and 2) thermal stress in a cyclic nucleotide independent manner.
Rembold
Christopher M
CM
Cardiovascular Division, Department of Internal Medicine, University of Virginia Health System, Charlottesville, Virginia 22908 USA. crembold@virginia.edu
Kaufman
Elizabeth
E
D000818:Animals; D017536:Carotid Artery, Common / Q000378:metabolism* / Q000502:physiology; D000242:Cyclic AMP / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D004056:Differential Threshold / Q000502:physiology; D050886:HSP20 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006632:Histamine / Q000502:physiology; D006358:Hot Temperature; D007526:Isoelectric Point; D009131:Muscle, Smooth, Vascular / Q000378:metabolism / Q000502:physiology; D018994:Myosin Light Chains / Q000378:metabolism / Q000502:physiology; D009712:Nucleotides, Cyclic / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D012694:Serine / Q000378:metabolism; D013552:Swine
D050886:HSP20 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D018994:Myosin Light Chains; D009712:Nucleotides, Cyclic; D010750:Phosphoproteins; D012694:Serine; D006632:Histamine; D000242:Cyclic AMP; D006152:Cyclic GMP