Table 3.

Cardiovascular status of 5°C- and 21°C-acclimated normoxic turtles before and after intra-arterial injection of the α-adrenergic antagonist phentolamine

Acclimation temperatureDrug injectedHeart rate fH (beats min−1)Systemic stroke volume Vssys (ml kg−1)Systemic cardiac output sys (ml min−1 kg−1)Systemic blood pressure Psys (kPa)Systemic power output POsys (mW g−1)Systemic resistance Rsys (kPa ml−1 min kg)
5°CRoutine normoxic4.1±0.4*2.31±0.379.2±1.3*1.52±0.11*0.126±0.025*0.18±0.03*
Phentolamine (3 mg kg−1)4.3±0.53.21±0.5712.8±1.80.98±0.060.108±0.0150.08±0.01
21°CRoutine normoxic21.3±2.01.95±0.29 (5)42.9±8.0 (5)2.83±0.531.508±0.323 (5)0.09±0.02 (5)
Phentolamine (3 mg kg−1)22.6±3.42.84±0.90 (4)63.5±18.6 (4)2.08±0.331.777±0.591 (4)0.06±0.02 (4)
  • Values are means ± s.e.m. (N=6, unless otherwise indicated in parentheses).

  • * Significant differences (P<0.05) between acclimation temperature for routine normoxic cardiovascular status.

  • Significant differences (P<0.05) between routine normoxic and phentolamine for each variable at each acclimation temperature.