ISSN:
1432-2013
Keywords:
Post-tetanic depression
;
Rat vas deferens
;
Smooth muscle
;
Presynaptic modulation and magnesium ions
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract The effects of different drugs on the post-tetanic twitch responses of the prostatic end of the isolation rat vas deferens were examined. Following repetitive field stimulation (4–5 Hz for 40–60 s), the post-tetanic twitches (0.2–0.5 Hz) were depressed relative to the steady-state pretetanic twiches. Maximum post-tetanic twitch depression (PTD) occurred 15–30 s after the tetanic stimulation. The PTD was not reversed but deepened and prolonged by the presynaptic α2-adrenoceptor antagonists idazoxan (RX 781094) or yohimbine (10−7 M) alone or combined with the neuronal uptake blocker, desipramine (10−6 M). The PTD was insensitive to the β-adrenoceptor blocker, propranolol (10−6 M), the P1-purinoceptor antagonist, 8-phenyltheophylline (10−5 M) or the prostaglandin E synthesis inhibitor, indomethacin (10−6 M). Pre- and post-tetanic contractions to superfused noradrenaline (NA), adenosine 5′-triphosphate (ATP), or β,γ-methylene ATP (β,γ-mATP) (bolus injections into superfusate, 1–8×10−5 M) were not significantly (p〈0.01) different. The PTD was absent in high magnesium (6.2–11.2 mM) solutions. These results are consistent with the PTD having an intrinsic presynaptic origin. They are discussed in relation to stimulation-induced modulation of transmitter release.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00581166
Permalink
