Respiratory effects of cyclic AMP following injection into the nucleus tractus solitarius of rats.
Rats were anesthetized with urethane and a limited occipital craniotomy was performed to expose the caudal medulla in the region of the obex. Injections were made into sites in the brainstem of spontaneously-breathing rats through glass micropipettes. Tidal volume, respiratory frequency, minute volume, blood pressure and heart rate were recorded before and after the administration of 8-bromoadenosine 3',5'-cyclic monophosphate (Br-cAMP), an analog of cyclic AMP. Injections of Br-cAMP into the ventromedial portion of the caudal nucleus tractus solitarius (NTS) produced dose-related decreases in pulmonary ventilation due to effects on both respiratory frequency, as well as minute volume. In larger doses, Br-cAMP produced periodic apnea and irregular breathing. The respiratory depression was accompanied by transient hypotension and bradycardia. The data indicate that cyclic AMP may function as a second messenger in respiratory control regions in the brainstem.
Barraco
R A
RA
Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan 48201.
Schoener
E P
EP
Polasek
P M
PM
Simpson
L L
LL
Janusz
C J
CJ
Parizon
M
M
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001933:Brain Stem / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D007267:Injections; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012119:Respiration / Q000187:drug effects*; D012129:Respiratory Function Tests
D015124:8-Bromo Cyclic Adenosine Monophosphate