TY - JOUR
T1 - Denervation-induced supersensitivity to calcium of chemically skinned smooth muscle of the guinea-pig vas deferens
AU - Ramos, K.
AU - Gerthoffer, W. T.
AU - Westfal, D. P.
N1 - Copyright:
Copyright 2004 Elsevier B.V., All rights reserved.
PY - 1986
Y1 - 1986
N2 - Chronic denervation of the smooth muscle of the guinea-pig vas deferens results in postjunctional supersensitivity. A partial membrane depolarization contributes to the enhanced sensitivity. However, there is evidence that supersensitivity results in part from cellular alterations other than membrane potential changes. In the present study we investigated the possibility that changes in the sensitivity of the contractile proteins may contribute to the phenomenon. The approach was to evaluate the concentration-response relationship for calcium of 'skinned' preparations of guinea-pig vas deferens. The tissues were chemically skinned with either triton X-100 or saponin. Concentration-response curves for calcium were constructed 1 week after postganglionic denervation of one of a pair of vas deferentia. The curve for denervated tissues was shifted significantly to the left of control (1.5-fold at the level of the EC50). In addition to supersensitivity, denervated skinned preparations exhibited a faster rate of contraction. The phenothiazine compounds trifluperazine, fluphenazine and chlorpromazine relaxed skinned muscles which were contracted with calcium. The relaxation was concentration-dependent, and was less pronounced in denervated vasa deferentia than in controls. These results suggest that increased sensitivity of the contractile proteins may contribute to the denervation-induced supersensitivity of smooth muscle, and further that this may be related to a change in the activity or amount of calmodulin
AB - Chronic denervation of the smooth muscle of the guinea-pig vas deferens results in postjunctional supersensitivity. A partial membrane depolarization contributes to the enhanced sensitivity. However, there is evidence that supersensitivity results in part from cellular alterations other than membrane potential changes. In the present study we investigated the possibility that changes in the sensitivity of the contractile proteins may contribute to the phenomenon. The approach was to evaluate the concentration-response relationship for calcium of 'skinned' preparations of guinea-pig vas deferens. The tissues were chemically skinned with either triton X-100 or saponin. Concentration-response curves for calcium were constructed 1 week after postganglionic denervation of one of a pair of vas deferentia. The curve for denervated tissues was shifted significantly to the left of control (1.5-fold at the level of the EC50). In addition to supersensitivity, denervated skinned preparations exhibited a faster rate of contraction. The phenothiazine compounds trifluperazine, fluphenazine and chlorpromazine relaxed skinned muscles which were contracted with calcium. The relaxation was concentration-dependent, and was less pronounced in denervated vasa deferentia than in controls. These results suggest that increased sensitivity of the contractile proteins may contribute to the denervation-induced supersensitivity of smooth muscle, and further that this may be related to a change in the activity or amount of calmodulin
UR - http://www.scopus.com/inward/record.url?scp=0022658097&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0022658097&partnerID=8YFLogxK
M3 - Article
C2 - 3941403
AN - SCOPUS:0022658097
SN - 0022-3565
VL - 236
SP - 80
EP - 84
JO - Journal of Pharmacology and Experimental Therapeutics
JF - Journal of Pharmacology and Experimental Therapeutics
IS - 1
ER -