The effects of pentobarbitone and urethane on pulmonary airway resistance in guinea-pigs and their interactions with drugs.
1 Propranolol increased pulmonary airway resistance (PAR) in the conscious guinea-pig, whereas atropine had no effect, suggesting the existence of a continual sympathetic bronchodilator tone. 2 The direct bronchoconstrictor effects of histamine, acetylcholine and 5-hydroxytryptamine were modified by autonomic reflexes: a bronchodilator one, abolished by propranolol, and a cholinergic bronchoconstrictor one, seen with histamine. 3 Pentobarbitone increased PAR, an effect which was reduced by propranolol but which was unaffected by atropine. The bronchoconstrictor effects of histamine, acetylcholine and 5-hydroxytryptamine were potentiated by pentobarbitone. 4 Pentobarbitone therefore appears to inhibit the adrenergic bronchodilator tone and to depress adrenergic reflexes, these being the preponderant autonomic influences in these experiments. 5 Like pentobarbitone, urethane increased PAR in the conscious guinea-pig and potentiated the bronchoconstrictor effects of the three amines. These actions are similarly attributed to a reduction in adrenergic influences.
D000403:Airway Resistance / Q000187:drug effects*; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D004347:Drug Interactions; D006168:Guinea Pigs; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D010424:Pentobarbital / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology; D014520:Urethane / Q000494:pharmacology*
D014520:Urethane; D001285:Atropine; D011433:Propranolol; D010424:Pentobarbital