title: Effects of salinity manipulations on blood pressures in an osmoconforming chordate, the hagfish, Eptatretus cirrhatus.
abstract: Arterial and venous pressures were measured in hagfishes subjected to acute changes in salinity. The osmotic pressure of the seawater (SW) was increased or decreased by approximately 10%. Sixty minutes after the change in medium osmolarity the osmotic pressure of the blood corresponded with that of the medium. Following transfer to 90% SW all measured parameters changed as predicted for a passive increase in blood volume, apart from the pressure in the posterior cardinal vein (PCV) which fell. By 2 h dorsal aortic (DA) pressure and pressure in the PCV and supraintestinal vein had returned to pre-change values. In contrast, following exposure to 110% SW, pressures fell and apart from the supraintestinal vein they remained low at 120 min. At 24 h, DA pressure was lower than pre-change values for both groups. The data are consistent with the concept of central venous tone being regulated in hagfishes, which cope better with volume expansion than volume depletion.
authors.affiliation: School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8020, New Zealand,
authors.forename: J M
authors.initials: JM
authors.lastname: Foster
authors.forename: M E
authors.initials: ME
authors.lastname: Forster
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D001810:Blood Volume / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology; D006196:Hagfishes / Q000502:physiology*; D009994:Osmolar Concentration; D012623:Seawater / Q000737:chemistry*; D012965:Sodium Chloride / Q000032:analysis; D013997:Time Factors; D014690:Venous Pressure / Q000502:physiology; D014882:Water-Electrolyte Balance / Q000502:physiology*
chemical_list: D012965:Sodium Chloride