title: Response of Northern Elephant Seal platelets to pressure and temperature changes: a comparison with human platelets.
abstract: Mammalian blood platelets are activated by physiological agonists such as collagen or thrombin, or by physical stimuli such as cold temperatures and rapid decompression. Marine mammals regularly experience cold temperatures, high pressures and rapid decompression while diving, yet do not appear to suffer from thrombotic events during routine dive activity. We evaluated the effects of cold temperature and high pressure excursions on Northern Elephant Seal (NES) platelets and compared NES platelet response to that of human platelets subjected to identical stimuli. NES platelets undergo cold-induced activation when chilled to 4 °C, and 3 distinct phase transitions can be measured using Fourier Transform Infrared Spectroscopy. NES platelet membrane lipid composition was determined using thin layer chromatography and NES platelets were found to have three times the amount of cholesterol (21% by weight) as human platelets. When exposed to high pressure-rapid decompression excursion, NES platelets did not undergo morphological shape change nor bind increased amounts of fibrinogen, while human platelets were significantly activated by the same excursion. These results demonstrate that while NES platelets are activated by the physical stimulus of cold temperatures, they are resistant to decompression-induced activation. We suggest that the composition of NES platelet membranes may play an important role in preventing pressure-related activation.
authors.affiliation: Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, Davis, CA 95616, USA. cara.field@gmail.com
authors.forename: Cara L
authors.initials: CL
authors.lastname: Field
authors.forename: Fern
authors.initials: F
authors.lastname: Tablin
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000378:metabolism / Q000502:physiology*; D048430:Cell Shape; D003080:Cold Temperature; D005260:Female; D005340:Fibrinogen / Q000378:metabolism; D006801:Humans; D006874:Hydrostatic Pressure; D008563:Membrane Lipids / Q000378:metabolism; D011485:Protein Binding; D046048:Seals, Earless / Q000097:blood*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D008563:Membrane Lipids; D005340:Fibrinogen