Cyclic subambient blood pressure in the dorsal intestinal vein of the spiny dogfish (Squalus acanthias)

Abstract

In restrained decerebrate unanaesthetised dogfish, blood pressure in the dorsal intestinal vein fell cyclically to -33 ± 11.9 cm H₂O for periods of 10.5 ± 5.8 min and then increased again to a positive pressure of +12.3 ± 4.3 cm H₂O, with a total cycle time of 20.6 ± 3.7 min, (n = 16 measurements). There were no significant changes in somatic or central venous pressure accompanying these cycles; intraintestinal and intra-abdominal pressures also changed little. How these subambient pressures might be sustained and their origin are discussed; it is suggested that they might be related to cyclic activity in the rectal gland.

Keywords:

• dogfish
• Squalus acanthias
• intestinal vein
• blood pressure
• subambient pressure
• rectal gland