Publication

The role of α1-adrenoceptor subtypes in the phasic and tonic responses to phenylephrine in the longitudinal smooth muscle of the rat portal vein

Schwietert, H. R., Gouw, M. A. M., Wilhelm, D., Wilffert, B. & Van Zwieten, P. A., 22-Oct-1991, In : Naunyn-Schmiedeberg's Archives of Pharmacology. 343, 5, p. 463-471 9 p.

Research output: Contribution to journalArticleAcademicpeer-review

APA

Schwietert, H. R., Gouw, M. A. M., Wilhelm, D., Wilffert, B., & Van Zwieten, P. A. (1991). The role of α1-adrenoceptor subtypes in the phasic and tonic responses to phenylephrine in the longitudinal smooth muscle of the rat portal vein. Naunyn-Schmiedeberg's Archives of Pharmacology, 343(5), 463-471.

Author

Schwietert, H.R. ; Gouw, M.A.M. ; Wilhelm, D. ; Wilffert, B. ; Van Zwieten, P.A. / The role of α1-adrenoceptor subtypes in the phasic and tonic responses to phenylephrine in the longitudinal smooth muscle of the rat portal vein. In: Naunyn-Schmiedeberg's Archives of Pharmacology. 1991 ; Vol. 343, No. 5. pp. 463-471.

Harvard

Schwietert, HR, Gouw, MAM, Wilhelm, D, Wilffert, B & Van Zwieten, PA 1991, 'The role of α1-adrenoceptor subtypes in the phasic and tonic responses to phenylephrine in the longitudinal smooth muscle of the rat portal vein', Naunyn-Schmiedeberg's Archives of Pharmacology, vol. 343, no. 5, pp. 463-471.

Standard

The role of α1-adrenoceptor subtypes in the phasic and tonic responses to phenylephrine in the longitudinal smooth muscle of the rat portal vein. / Schwietert, H.R.; Gouw, M.A.M.; Wilhelm, D.; Wilffert, B.; Van Zwieten, P.A.

In: Naunyn-Schmiedeberg's Archives of Pharmacology, Vol. 343, No. 5, 22.10.1991, p. 463-471.

Research output: Contribution to journalArticleAcademicpeer-review

Vancouver

Schwietert HR, Gouw MAM, Wilhelm D, Wilffert B, Van Zwieten PA. The role of α1-adrenoceptor subtypes in the phasic and tonic responses to phenylephrine in the longitudinal smooth muscle of the rat portal vein. Naunyn-Schmiedeberg's Archives of Pharmacology. 1991 Oct 22;343(5):463-471.


BibTeX

@article{544ba4bf135f437f98ef3d0e6770ce0a,
title = "The role of α1-adrenoceptor subtypes in the phasic and tonic responses to phenylephrine in the longitudinal smooth muscle of the rat portal vein",
abstract = "The purpose of this investigation was to determine whether α1-adrenoceptor subtypes (co)exist in the rat portal vein and, if so, whether they could be functionally associated with the phasic and tonic types of contraction as a response to α1-adrenoceptor stimulation by phenylephrine. A low Ca2+concentration (0.9 mmol/l) in the Tyrode solution enabled us to quantify changes both in the phasic myogenic activity and in the basal tone of the rat portal vein preparation very precisely. We used both competitive and non-competitive α-adrenoceptor antagonists which have been employed successfully by other investigators to discriminate between α1-adrenoceptor subtypes in vascular and other tissues. Schild analysis showed that the competitive α-adrenoceptor antagonists prazosin, phentolamine, yohimbine, corynanthine, idazoxan, rauwolscine and 5-methyl-urapidil could not distinguish between the phasic and tonic responses to phenylephrine and/or different α1-adrenoceptor subtypes in the rat portal vein. However, when we compared our pA2values with those found to be representative indicators according to subclassifications based on the use of selective antagonists in different tissues, the α1-adrenoceptors in the rat portal vein appeared to belong to the α(1L)- or α(1a)-subtype. This subclassification was not in accordance with the data obtained with the irreversible α-adrenoceptor antagonist chloroethylclonidine. However, the validity of this alkylating agent as a tool for receptor classification was restricted, at least in the rat portal vein, by its effects on receptor reserve. In contrast to the competitive α-adrenoceptor antagonists, the irreversible α-adrenoceptor antagonists phenoxybenzamine and chloroethylclonidine could indeed discriminate between the phasic and tonic types of contraction in response to α1-adrenoceptor stimulation by phenylephrine, indicating two different receptor reserves for phenylephrine for the two types of responses. In conclusion, both the phasic and tonic types of contraction elicited by phenylephrine in the longitudinal smooth muscle of the rat portal vein appear to be mediated by one particular α1-adrenoceptor subtype as defined by Schild analysis with selective, competitive α-adrenoceptor antagonists. However, using the method of receptor alkylation with phenoxybenzamine, two different affinity constants for the two types of responses could be calculated for phenylephrine. This may reflect the involvement of two different subtypes of α1-adrenoceptors or, more probably, the existence of only one α1-adrenoceptor subtype, which is coupled with two different intrinsic efficacies to the effector pathways mediating the phasic and tonic responses, respectively.",
keywords = "α1-adrenoceptor subtypes, phasic contraction, phenylephrine, rat portal vein, tonic contraction, 5 methylurapidil, alpha 1 adrenergic receptor, alpha adrenergic receptor blocking agent, chloroethylclonidine, corynanthine, idazoxan, phenoxybenzamine, phentolamine, prazosin, rauwolscine, receptor subtype, yohimbine, animal tissue, article, concentration response, controlled study, extracellular calcium, male, nonhuman, portal vein, priority journal, rat, smooth muscle contractility, smooth muscle tone",
author = "H.R. Schwietert and M.A.M. Gouw and D. Wilhelm and B. Wilffert and {Van Zwieten}, P.A.",
year = "1991",
month = "10",
day = "22",
language = "English",
volume = "343",
pages = "463--471",
journal = "Naunyn-Schmiedebergs Archives of Pharmacology",
issn = "0028-1298",
publisher = "SPRINGER",
number = "5",

}

RIS

TY - JOUR

T1 - The role of α1-adrenoceptor subtypes in the phasic and tonic responses to phenylephrine in the longitudinal smooth muscle of the rat portal vein

AU - Schwietert, H.R.

AU - Gouw, M.A.M.

AU - Wilhelm, D.

AU - Wilffert, B.

AU - Van Zwieten, P.A.

PY - 1991/10/22

Y1 - 1991/10/22

N2 - The purpose of this investigation was to determine whether α1-adrenoceptor subtypes (co)exist in the rat portal vein and, if so, whether they could be functionally associated with the phasic and tonic types of contraction as a response to α1-adrenoceptor stimulation by phenylephrine. A low Ca2+concentration (0.9 mmol/l) in the Tyrode solution enabled us to quantify changes both in the phasic myogenic activity and in the basal tone of the rat portal vein preparation very precisely. We used both competitive and non-competitive α-adrenoceptor antagonists which have been employed successfully by other investigators to discriminate between α1-adrenoceptor subtypes in vascular and other tissues. Schild analysis showed that the competitive α-adrenoceptor antagonists prazosin, phentolamine, yohimbine, corynanthine, idazoxan, rauwolscine and 5-methyl-urapidil could not distinguish between the phasic and tonic responses to phenylephrine and/or different α1-adrenoceptor subtypes in the rat portal vein. However, when we compared our pA2values with those found to be representative indicators according to subclassifications based on the use of selective antagonists in different tissues, the α1-adrenoceptors in the rat portal vein appeared to belong to the α(1L)- or α(1a)-subtype. This subclassification was not in accordance with the data obtained with the irreversible α-adrenoceptor antagonist chloroethylclonidine. However, the validity of this alkylating agent as a tool for receptor classification was restricted, at least in the rat portal vein, by its effects on receptor reserve. In contrast to the competitive α-adrenoceptor antagonists, the irreversible α-adrenoceptor antagonists phenoxybenzamine and chloroethylclonidine could indeed discriminate between the phasic and tonic types of contraction in response to α1-adrenoceptor stimulation by phenylephrine, indicating two different receptor reserves for phenylephrine for the two types of responses. In conclusion, both the phasic and tonic types of contraction elicited by phenylephrine in the longitudinal smooth muscle of the rat portal vein appear to be mediated by one particular α1-adrenoceptor subtype as defined by Schild analysis with selective, competitive α-adrenoceptor antagonists. However, using the method of receptor alkylation with phenoxybenzamine, two different affinity constants for the two types of responses could be calculated for phenylephrine. This may reflect the involvement of two different subtypes of α1-adrenoceptors or, more probably, the existence of only one α1-adrenoceptor subtype, which is coupled with two different intrinsic efficacies to the effector pathways mediating the phasic and tonic responses, respectively.

AB - The purpose of this investigation was to determine whether α1-adrenoceptor subtypes (co)exist in the rat portal vein and, if so, whether they could be functionally associated with the phasic and tonic types of contraction as a response to α1-adrenoceptor stimulation by phenylephrine. A low Ca2+concentration (0.9 mmol/l) in the Tyrode solution enabled us to quantify changes both in the phasic myogenic activity and in the basal tone of the rat portal vein preparation very precisely. We used both competitive and non-competitive α-adrenoceptor antagonists which have been employed successfully by other investigators to discriminate between α1-adrenoceptor subtypes in vascular and other tissues. Schild analysis showed that the competitive α-adrenoceptor antagonists prazosin, phentolamine, yohimbine, corynanthine, idazoxan, rauwolscine and 5-methyl-urapidil could not distinguish between the phasic and tonic responses to phenylephrine and/or different α1-adrenoceptor subtypes in the rat portal vein. However, when we compared our pA2values with those found to be representative indicators according to subclassifications based on the use of selective antagonists in different tissues, the α1-adrenoceptors in the rat portal vein appeared to belong to the α(1L)- or α(1a)-subtype. This subclassification was not in accordance with the data obtained with the irreversible α-adrenoceptor antagonist chloroethylclonidine. However, the validity of this alkylating agent as a tool for receptor classification was restricted, at least in the rat portal vein, by its effects on receptor reserve. In contrast to the competitive α-adrenoceptor antagonists, the irreversible α-adrenoceptor antagonists phenoxybenzamine and chloroethylclonidine could indeed discriminate between the phasic and tonic types of contraction in response to α1-adrenoceptor stimulation by phenylephrine, indicating two different receptor reserves for phenylephrine for the two types of responses. In conclusion, both the phasic and tonic types of contraction elicited by phenylephrine in the longitudinal smooth muscle of the rat portal vein appear to be mediated by one particular α1-adrenoceptor subtype as defined by Schild analysis with selective, competitive α-adrenoceptor antagonists. However, using the method of receptor alkylation with phenoxybenzamine, two different affinity constants for the two types of responses could be calculated for phenylephrine. This may reflect the involvement of two different subtypes of α1-adrenoceptors or, more probably, the existence of only one α1-adrenoceptor subtype, which is coupled with two different intrinsic efficacies to the effector pathways mediating the phasic and tonic responses, respectively.

KW - α1-adrenoceptor subtypes

KW - phasic contraction

KW - phenylephrine

KW - rat portal vein

KW - tonic contraction

KW - 5 methylurapidil

KW - alpha 1 adrenergic receptor

KW - alpha adrenergic receptor blocking agent

KW - chloroethylclonidine

KW - corynanthine

KW - idazoxan

KW - phenoxybenzamine

KW - phentolamine

KW - prazosin

KW - rauwolscine

KW - receptor subtype

KW - yohimbine

KW - animal tissue

KW - article

KW - concentration response

KW - controlled study

KW - extracellular calcium

KW - male

KW - nonhuman

KW - portal vein

KW - priority journal

KW - rat

KW - smooth muscle contractility

KW - smooth muscle tone

M3 - Article

VL - 343

SP - 463

EP - 471

JO - Naunyn-Schmiedebergs Archives of Pharmacology

JF - Naunyn-Schmiedebergs Archives of Pharmacology

SN - 0028-1298

IS - 5

ER -

ID: 14136314