Blood flow and pressure in the giraffe carotid artery

1. Carotid artery blood pressure and blood flow were measured and telemetered from wild giraffes ranging freely on the African plains.
2. The blood pressure ranged between 260/160 mm Hg when the animal was lying flat, and 120/75 mm Hg when it was standing upright; dp/dt at the onset of systole was 1500 mm/sec.
3. Peak systolic blood velocity measured at the same site was 60 cm/sec; during diastole velocity remained above 40 cm/sec. Calculated blood flow in the carotid artery ranged between 50cm³/sec in the prone animal, and 35 cm³/sec in the standing.
4. XY plots of the flow and pressure produced open clockwise loops which varied in shape with activity and posture; such phase differences probably reflect mechanical properties peculiar to the giraffe's arterial system.

Keywords: cerebral circulation, carotid system, pressure flow relations, Masai giraffe,
Authors: Robert L. Van Citters, William S. Kemper, and Dean L. Franklin
Journal: Comparative Biochemistry and Physiology