Effect of acute haemodilution on right atrial type-A receptor activity and right atrial pressure in anaesthetized cats.
To determine the effects of acute haemodilution on right atrial pressure and right atrial type-A receptor activity, experiments were conducted in nine anaesthetized cats. Haemodilution was induced by replacement of blood by same volume of dextran (molecular weight-150000). Arterial blood pressure, right atrial pressure and right atrial type-A receptor activity were recorded. Hematocrit, arterial blood pO2, pCO2, and pH were measured. Mean arterial blood pressure, pO2, pCO2, and pH were not altered by haemodilution which extended to a hematocrit level of about 13%. Mean right atrial pressure, 'a' wave pressure showed significant changes after 2nd and 3rd exchange. Heart rate and 'a' wave amplitude changed significantly (P < 0.05) after 3rd exchange. The amplitude of the 'a' wave was increased from 3.57 +/- 0.93 to 5.79 +/- 1.46 cm H2O, heart rate was increased from 163.89 +/- 5.36 to 169.22 +/- 4.84 beats/min, mean right atrial pressure was increased from 2.85 +/- 0.31 to 4.61 +/- 0.27 cm H2O, initial 'a' wave pressure was increased from 1.78 +/- 0.09 to 5.06 +/- 0.44 cm H2O. The data indicate that under present experimental conditions, the activity of the type-A receptor did not show any significant change (P > 0.05) on acute haemodilution. Significant increase (P < 0.05) in the amplitude of 'a' wave, mean right atrial pressure and initial 'a' wave pressure could be attributed to increased myocardial contractility.
Bhunia
S
S
Department of Physiology, Vallabhbhai Patel Chest Institute, University of Delhi.
Fahim
M
M
D000818:Animals; D016275:Atrial Function; D016280:Atrial Function, Right / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D002245:Carbon Dioxide / Q000097:blood; D002415:Cats; D003911:Dextrans / Q000494:pharmacology; D006325:Heart Atria / Q000648:ultrastructure; D006400:Hematocrit; D006438:Hemodilution; D006863:Hydrogen-Ion Concentration; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D011311:Pressoreceptors / Q000502:physiology*
D003911:Dextrans; D002245:Carbon Dioxide; D010100:Oxygen