A homeostatic adaptive response to alpha-methyl-dopa in conscious dogs.
Repeated daily administration of an oral dose of 1000 mg of alpha-methyl-dopa (methyl dopa) to conscious dogs produced a conditioned adaptive hypertensive systolic and diastolic arterial pressure response along with the direct hypotensive pharmacological effect. The lower dose of 500 mg/day appeared to be devoid of direct or adaptive response effects, while the higher dose of 2000 mg/day only produced a blood pressure lowering response. The abrupt drug withdrawal unmasking the homeostatic state resulted in a marked systolic and diastolic pressor response which endured for about 10-days with peak effect reached at 17-days after termination of drug treatment. Comparable results were obtained whether the dogs were evaluated while in their normal horizontal body position or in a repositional upright condition.
D000222:Adaptation, Physiological; D000284:Administration, Oral; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D001921:Brain / Q000378:metabolism; D003213:Conditioning, Psychological / Q000187:drug effects; D004285:Dogs; D006339:Heart Rate / Q000187:drug effects*; D006706:Homeostasis / Q000187:drug effects*; D008750:Methyldopa / Q000008:administration & dosage / Q000494:pharmacology*; D009638:Norepinephrine / Q000096:biosynthesis; D011187:Posture; D013997:Time Factors
D008750:Methyldopa; D009638:Norepinephrine