Bauhaus-Universität Weimar

Titel:
Vasor-Motor Nerves of the Limbs. Abstract (of No. XXI) [From the Proceedings of the American Association for the Advancement of Science, Vol. XXXV. Buffalo Meeting, August, 1886, Offprint]
Person:
Bowditch, H. P.
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit39652/1/
[From the Proceedings of the American Association for the advancement 
of Science, Vol. XXXV. Buffalo Meeting, August, 1886.] 
Vaso-motor nerves of the limbs. By Dr. H. P. Bowditch, Harvard 
Medical School, Boston, Mass. 
[abstract.] 
In most of the recent experiments on the vaso-motor nerves of the 
limbs, the temperature of t-lie skin has been taken as the index of vaso-mo¬ 
tor activity. It is evident, however, that by this method transitory changes 
cannot be recorded and quantitative results cannot be obtained. In exper¬ 
iments made with the pletliysmographic method, to which these objections 
do not apply, it was found that either a constriction, or a constriction fol¬ 
lowed by a dilatation, or a dilatation of the vessels of the leg, may be pro¬ 
duced by an electric stimulation of the sciatic nerve. The character of 
the result depends largely upon the strength and rapidity of the induction 
shocks used as a stimulus. In the following table are given the results 
of 909 observations of the effect of stimulations of the sciatic nerve with 
induction shocks of varying intensity and rate. 
Bate of 
Stimulation. 
WEAK. 
MEDIUM. 
STRONG. 
No.ol 
Obs. 
Per cent 
No. Of 
Obs. 
Ter cent 
No. of 
Obs. 
Per cent 
- 
-+ 
+ 
- 
+ 
- 
-+* 
4* 
0-4 in 1" 
5-16 in 1" 
30-64 in 1" 
108 
69 
62 
9.3 
31.9 
48.4 
57.4 
60.9 
50.0 
33.3 
7.2 
1.6 
218 
153 
40 
7.8 
28.8 
50.0 
69.7 
58.8 
50.0 
22.5 
12.4 
0. 
142 
109 
8 
6.3 
5.5 
37.5 
69.7 
89.9 
62.5 
23.9 
4.6 
0. 
The figures in the columns headed —, — -f- and -f- show in what per cent 
of the total number of observations the effect of the stimulation of each 
rate and strength was respectively a constriction, a constriction followed 
by a dilatation and a dilatation. It will be observed: 1. That with each 
rate and intensity of stimulation the result, in at least one-lialf of the ob¬ 
servations, is a constriction followed by a dilatation; 2. That with an 
increasing rate of stimulation the proportion of cases giving a simple dila¬ 
tation diminishes while (except with strong stimulations) that of cases 
giving a simple constriction increases. 
With slow irritations it was found that dilatations are more readily pro¬ 
duced with feeble than with strong irritations. Experiments with animals 
whose nerves had been cut several days previously showed that degenera¬ 
tion of the nerve causes the loss of its constricting earlier than that of its 
dilating power. 
It thus appears that the sciatic nerve contains fibres which both con¬ 
tract and dilate the vessels ; but the former effect being more prompt than 
the latter, both in its appearance and disappearance, the two effects never 
neutralize each other. 
A fresh nerve with a strong and rapid stimulation are the best condi¬ 
tions for producing constriction. A degenerated nerve with a feeble and 
slow stimulation are the best conditions for producing dilatation. 
(270) 
Salem Press, December, 1886.
        

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