Age-dependent modulation of neuropeptide Y on adrenergic transmission of guinea pig vas deferens.
1. The effect of neuropeptide (NPY) on [3H]noradrenaline ([3H]NA) release- and on contractions evoked by field electrical stimulation (FES) was studied in vitro in vas deferens from mature and immature guinea pigs. 2. The evoked tritium overflow (which reflected [3H]NA release) was determined by liquid scintillation spectrometry. 3. Field electrical stimulation of 5 Hz (trains of 50 pulses in 20 sec intervals) evoked guanethidine-sensitive contractions. 4. NPY (0.01-1 microM) dose-dependently inhibited the evoked contractions in both groups of animals. NPY, 1 microM, almost completely inhibited the evoked contractions in mature animals, while those in immature guinea pigs were inhibited but only by 80.4 +/- 3.6%. 5. The amount of tritium overflow evoked by 5 Hz stimulation (300 pulses: 15 trains of 20 pulses in 20 sec intervals) was higher in immature guinea pigs (0.46 +/- 0.03%) compared with the amount of the evoked tritium overflow in mature guinea pigs (0.39 +/- 0.02%). 6. NPY, 1 microM, inhibited the evoked tritium overflow. The NPY inhibition was more pronounced in vas deferens of mature (45.3 +/- 2.0%) than in immature (25.1 +/- 3.5%) guinea pigs. 7. The results suggest that NPY modulation of adrenergic transmission at the prejunctional level increases with the maturity.
Chernaeva
L
L
Institute of Physiology, Bulgarian Academy of Sciences, Sofia.
Yankova
M
M
D000320:Adrenergic Fibers / Q000187:drug effects / Q000502:physiology; D000375:Aging / Q000502:physiology; D000818:Animals; D004558:Electric Stimulation; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009478:Neuropeptide Y / Q000494:pharmacology*; D009638:Norepinephrine / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects* / Q000502:physiology; D014649:Vas Deferens / Q000187:drug effects / Q000294:innervation* / Q000502:physiology
D009478:Neuropeptide Y; D009638:Norepinephrine