Degeneration activity after parasympathetic or sympathetic denervation

Cholinergic sensitivity of irides from donors with various pathological conditions and lens implants

In vitro, iris contractions after muscarinic agonists were measured in mg of tension change and the concentration producing 50% of the response was expressed as EC50 mumol/l. Although the average EC50 value of carbachol in the iris sphincter of the donors with diabetes or Parkinson's disease did not change significantly when compared with the control, the maximum contraction of the tissue from the diseased state was increased significantly. Thus, in addition to the well known denervation supersensitivity of the iris-dilator, the iris-sphincter also develops adaptive sensitivity changes. Antimuscarinic drug treatment in some Parkinson's patients interfered with the estimation of supersensitivity in vitro studies. The enhanced response of carbachol at the low temperatures or the relative potency of carbachol and pilocarpine in the tissue obtained from the diseased donors was not significantly different from that of controls. Based on EC50 values, the potency of arecoline on the iris was 1/3 that of carbachol. Significantly lower EC50 values of carbachol were found in irides which were in contact with open loop type anterior chamber lens implants compared with those in contact with the closed loop anterior chamber lens implants. Maximum responses of irides to carbachol were less when the tissue was in contact with open loop lens compared with those in contact with closed loop anterior chamber implants. Irides from many donors having unilateral or bilateral replacement of the artificial lenses responded with EC50 of carbachol which was approximately equal to that of the contralateral eye. The maximum difference between EC50 values of the left and right iris was less than 5 fold.(ABSTRACT TRUNCATED AT 250 WORDS)

Disappearance of noradrenaline from different parts of the rabbit external ear following superior cervical ganglionectomy

Following superior cervical ganglionectomy the noradrenaline tissue levels in the base of the rabbit external ear started to decrease after about 12 hours. About 4 hours later noradrenaline started to decrease about simultaneously in the middle piece and the tip. Within 24 hours after ganglionectomy the noradrenaline decreased rapidly in all three pieces. Thereafter the noradrenaline of the base piece was levelling off at about 15% of the normal whereas the noradrenaline in the two other pieces remained at about 40% of the normal. The results indicate that the adrenergic innervation of the ear is complex, but that the base piece is supplied with adrenergic axons that are shorter than those of the middle and tip pieces. Based on 1: the delay of 4 hours observed in the pattern of the noradrenaline disappearance between the base and the two other pieces, and II: the difference in distance between the three pieces of the ear and the superior cervical ganglion, a transport rate of a "protecting factor" could be discussed to be about 1-2 cm/h. The rate of axonal transport of dopamine-beta-hydroxylase in the rabbit sciatic nerve, was found to be within the same range, being about 2 cm/h.

Effects of long term denervation on smooth muscle of the chicken expansor secundariorum

Denervation of the expansor secundariorum muscle of the adult and 2 week chicken, by sectioning the brachial plexus, resulted in an approximate twofold increase in dry weight over 8 weeks. Unlike skeletal muscle, no ultrastructural changes were exhibited by the smooth muscle cells for a period of up to 5 months post denervation. No evidence of hypertrophy of the individual muscle cells was observed, but following colchicine treatment a definite increase in the number of mitotic figures was noted within muscle bundles indicating that the increase in dry weight of the expansor muscle is due to hyperplasia of the smooth muscle cells. The results are discussed in relation to in vitro studies of the interaction of sympathetic nerves with smooth muscle.

[Sialoadenosis produced by drug-treatment of hypertonicity. I. Experimental studies on the effects of guanethidine (Ismelin) on the parotid glands of the rat (author's transl)]

48 rats were treated with the antihypertensive drug, guanethidine; its effects on the parotid glands (alpha-amylase content, protein concentration, and isamylase distribution patterns) were investigated. The treatment significantly increased the amylase activity in the gland extracts as well as the concentration of isoamylases and their specific enzyme activities. Moreover, we found a redistribution of activity between the 4 isoamylases of the parotid glands. The observed changes are the manifestations of a proteodyschylia concomitant with a peripheral neurogenic sialoadenosis. The described alterations are fully reversible within two weeks after discontinuation of the guanethidine application.

Degeneration secretion of saliva in the rat following sympathectomy

1. After previous extirpation of the superior cervical ganglion saliva was found to flow from the cannulated submaxillary duct of rats under chloralose anaesthesia. The secretion started 13-14.5 hr after sympathectomy, increased gradually in rate and then slowed down and ceased, lasting for about 12 hr.2. Injection of alpha- or beta-adrenoreceptor blocking drugs reduced the flow and a combination of both types of drugs abolished it. It is concluded that the secretion was caused by noradrenaline released from the degenerating nerves, and that the phenomenon is an example of the degeneration activity described in other preparations as an effect of section of post-ganglionic autonomic nerves.3. A similar, but less pronounced, secretion was found in the parotid gland of the rat.