We have examined the effects of centrally applied neuropeptides on ventilation (respiratory rate, tidal volume, and minute ventilation) in urethane-anesthetized rats. TRH caused an increase in respiratory rate, a decrease in tidal volume, but an increase in net minute ventilation. One TRH metabolite, acid TRH, caused similar changes, but no effect was observed from the other TRH metabolite, cHis-Pro. Both bombesin and calcitonin caused increases in minute ventilation due to increases in respiratory rate and tidal volume. Additionally, bombesin induced periodic sighing respirations at rates up to 15/minute which was observed with no other neuropeptide. Substance P, somatostatin, and neurotensin had no effect upon ventilation variables.
Bibliographical noteFunding Information:
The peptides were obtained commercially: bombesin (0.1-10.0 /xg ICV: Sigma Chemical Company, St. Louis, MO); neurotensin (10/xg ICV: Vega Chemicals, Reno, NV); thyrotropin releasing hormone (TRH 0.1-10.0 /xg ICV: Boehringer-Mannheim, Indianapolis, IN); somatostatin (10 /xg ICV: Beckman, Palo Alto, CA); pyro-glutamyl histidyl proline (acid TRH 1.0-10.0 tzg ICV: Vega Biochemicals, Tuscon, AZ); substance P (10/zg ICV: Vega Biochemicals, Tucson, AZ); calcitonin (0.02-2.0 units ICV: Armour Pharmaceutical Company, Phoenix, AZ), histidyl-proline di-latopiperazine (cHis-Pro 10 /zg ICV: Vega Biochemicals Company, Tucson, AZ). All peptides were administered ICV in five microliters of physiological saline. Control animals ~This work was supported by the Veterans Administration Research Service. 2Requests for reprints should be addressed to John E. Morley, M.B., B. Ch., Minneapolis VA Medical Center, Minneapolis, MN 55417.
- Substance P