Role of medullary emetic chemoreceptor trigger zone (CT zone) in postnephrectomy vomiting in dogs

¹ Department of Pharmacology, University of Utah College of Medicine, Salt Lake City, Utah

Latencies for vomiting following bilateral nephrectomy in control dogs, after gut denervation by transthoracic vagotomy and spinal cord transection at T₄, and after ineffective ablation of the CT zone, were all within a range of 16–48 hours. By contrast, in dogs with effective lesions of the CT zone, the latency for vomiting after nephrectomy was prolonged to a range of 54–147 hours and two dogs died after 5 and 6 days, respectively, without vomiting. Chlorpromazine and morphine did not prolong the latency for vomiting after nephrectomy. Guanidine hydrochloride, 75 mg/kg i.v., evoked vomiting in all of seven control dogs, but only in one of nine dogs with effective lesions of the CT zone. Except for a more rapid decline of serum chloride in control dogs, serum sodium, potassium, bicarbonate and blood urea nitrogen followed the same pattern after nephrectomy in control and CT-zone ablated dogs.