Effect of temperature on beta receptor responsiveness in guinea pig pulmonary tissues

Cumulative concentration-effect relationships of isoproterenol (isoprenaline) on guinea pig tracheal spirals and lung parenchymal strips were determined in organ baths kept at 37 degrees C or at 18 degrees C. The IC50's for isoproterenol at 18 degrees C were significantly (p less than .01) higher than those for isoproterenol at 37 degrees C in both the tissues; although the parenchymal response was affected more than that of the trachea by cooling. pA2 values for propranolol were determined on both tracheal spirals and parenchymal strips at 37 degrees C and 18 degrees C. The pA2 values were decreased in both the tissues by cooling. The decrease was more prominent in the parenchyma than in the trachea, a finding consistent with the concentration-effect relationships studies mentioned above.