ISSN:
1432-1912
Keywords:
6-Hydroxydopamine
;
Nictitating Membrane
;
Degeneration Contraction
;
Supersensitivity to Noradrenaline
;
Chemical Denervation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary After subcutaneous injection of 30 mg/kg of 6-hydroxydopamine into the conscious cat the denervated and the decentralized nictitating membranes contracted immediately. While the response of the denervated membrane is of short duration (1.5 h), the decentralized membrane is half relaxed after 11 h. The duration of the latter contraction is similar to that of the degeneration contraction seen after surgical denervation. It is proposed that the response of the decentralized nictitating membrane to 6-hydroxydopamine corresponds to the degeneration contraction. Treatment of the cats with pargyline prolongs both types of degeneration contractions. However, while beta-TMlO {[2-(2,6-dimethylphenoxy)propyl] trimethylammonium chloride had profound effects on the degeneration contraction seen after surgical denervation, it failed to affect that after 6-hydroxydopamine. Indirectly acting sympathomimetic amines prevented the usual effect of beta-TMlO on the degeneration contraction seen after surgical denervation. It is proposed that the failure of beta-TMlO to affect the response of the decentralized nictitating membrane to 6-hydroxydopamine is due to a similar preventive effect of 6-hydroxydopamine. The development of supersensitivity to (-)-noradrenaline was determined at various time intervals after the injection of 6-hydroxydopamine; pithed cats and isolated nictitating membranes were used. Under both conditions the membranes were in a state of sustained contraction, if the experiment was begun before the response of the decentralized nictitating membrane to 6-hydroxydopamine had worn off. After 6-hydroxydopamine the development of supersensitivity coincided with the falling phase of the degeneration contraction. Very similar results had been obtained earlier during the degeneration contraction after surgical denervation; the temporal relation between degeneration contraction and development of supersensitivity is very similar after surgical and chemical denervation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00997023
Permalink
