Ganglionic and arterial release of neuropeptide Y by bullfrog sympathetic neurons.
Sympathetic C neurons in lumbar paravertebral ganglia of the bullfrog have previously been shown to be vasomotor in function and to express neuropeptide Y (NPY). In the present experiments, a sensitive radioimmunoassay was used to measure the NPY content of ganglia and the descending abdominal aorta and to measure the overflow of NPY evoked by depolarizing concentrations of K+. Paravertebral ganglia 9 and 10 contain 3.1 pg NPY/micrograms protein and the aorta contains 0.18 pg NPY/micrograms protein. During 20-min depolarizations in high K+ (58 mM) Ringer, the ganglia released approximately 5% of their NPY content and the aorta released approximately 2% of its NPY content. Pretreatment of the tissues with Ringer containing 0.18 mM Ca2+, 8 mM Mg2+, and 1 mM Co2+ blocked the NPY release elicited by high K+. These findings provide further evidence that NPY is a postganglionic co-transmitter in sympathetic C neurons of the bullfrog.
Thorne
R
R
Department of Physiology, University of Pittsburgh School of Medicine, Pennsylvania 15261.
Smith
M S
MS
Horn
J P
JP
D000818:Animals; D001001:Anura; D001012:Aorta, Abdominal / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology; D005728:Ganglia, Sympathetic / Q000378:metabolism*; D007552:Isotonic Solutions / Q000494:pharmacology; D009474:Neurons / Q000378:metabolism*; D009478:Neuropeptide Y / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D011863:Radioimmunoassay; D000077331:Ringer's Solution
D007552:Isotonic Solutions; D009478:Neuropeptide Y; D000077331:Ringer's Solution; D011188:Potassium; D002118:Calcium