ETA receptors are the primary mediators of myofilament calcium sensitization induced by ET-1 in rat pulmonary artery smooth muscle: a tyrosine kinase independent pathway

A M Evans, H J Cobban, G F Nixon

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

1 We have investigated the possibility that ET-1 can induce an increase in myofilament calcium sensitivity in pulmonary artery smooth muscle. Arterial rings were permeabilized using a-toxin (120 mu g ml(-1)), in the presence of A23187 (10 mu M) to 'knock out' Ca2+ stores, and pre-constricted with pCa 6.8 (buffered with 10 mM EGTA). In the presence of this fixed Ca2+ concentration, 1 mu M ET-I induced a sustained, reversible constriction of 0.15 mN.

2 Pulmonary arterial rings were freeze-clamped at the peak of the induced constriction (time matched). Subsequent densitometric analysis revealed that ET-I (1 mu M) increased the level of phosphorylated myosin light chains by 34% compared to an 11% increase in the presence of pCa 6.8 alone.

3 In contrast to ET-1, the selective ETB receptor agonist Sarafotoxin S6C (100 nh I) failed to induce a significant constriction.

4 The constriction induced by 1 mu M ET-I was reversibly inhibited when the preparation was preincubated (15 min) with the ETA receptor antagonist BQ 123 (100 mu M). The constriction measured 0.13 mN in the absence and 0.07 mN in the presence of 100 mu M BQ 123.

5 In contrast, the constriction induced by 1 mu M ET-I measured 0.19 mN in the absence and 0.175 mN following a 15 min pre-incubation with the ETB antagonist BQ 788 (100 mu M).

6 The constriction induced by 1 mu M ET-I measured 0.14 mN in the presence and 0.13 mN following pre-incubation with the tyrosine kinase inhibitor Tyrphostin A23 (100 mu M).

7 We conclude that ET-1 induced an increase in myofilament calcium sensitivity in rat pulmonary arteries via the activation of ETA receptors and by a mechanism(s) independent of tyrosine kinase.

Original languageEnglish
Pages (from-to)153-160
Number of pages8
JournalBritish Journal of Pharmacology
Volume127
Publication statusPublished - 1999

Keywords

  • smooth muscle
  • pulmonary artery
  • ET-1
  • ETA
  • ETB
  • calcium sensitization
  • MYOSIN LIGHT CHAIN
  • RABBIT MESENTERIC-ARTERY
  • ENDOTHELIN RECEPTOR
  • GENE-EXPRESSION
  • HYPOXIC VASOCONSTRICTION
  • CONTRACTILE RESPONSE
  • CA2+ SENSITIVITY
  • HYPERTENSION
  • PHOSPHORYLATION
  • ANTAGONIST

Cite this

@article{882502fa0a0a4741bf784c149bdd3df0,
title = "ETA receptors are the primary mediators of myofilament calcium sensitization induced by ET-1 in rat pulmonary artery smooth muscle: a tyrosine kinase independent pathway",
abstract = "1 We have investigated the possibility that ET-1 can induce an increase in myofilament calcium sensitivity in pulmonary artery smooth muscle. Arterial rings were permeabilized using a-toxin (120 mu g ml(-1)), in the presence of A23187 (10 mu M) to 'knock out' Ca2+ stores, and pre-constricted with pCa 6.8 (buffered with 10 mM EGTA). In the presence of this fixed Ca2+ concentration, 1 mu M ET-I induced a sustained, reversible constriction of 0.15 mN.2 Pulmonary arterial rings were freeze-clamped at the peak of the induced constriction (time matched). Subsequent densitometric analysis revealed that ET-I (1 mu M) increased the level of phosphorylated myosin light chains by 34{\%} compared to an 11{\%} increase in the presence of pCa 6.8 alone.3 In contrast to ET-1, the selective ETB receptor agonist Sarafotoxin S6C (100 nh I) failed to induce a significant constriction.4 The constriction induced by 1 mu M ET-I was reversibly inhibited when the preparation was preincubated (15 min) with the ETA receptor antagonist BQ 123 (100 mu M). The constriction measured 0.13 mN in the absence and 0.07 mN in the presence of 100 mu M BQ 123.5 In contrast, the constriction induced by 1 mu M ET-I measured 0.19 mN in the absence and 0.175 mN following a 15 min pre-incubation with the ETB antagonist BQ 788 (100 mu M).6 The constriction induced by 1 mu M ET-I measured 0.14 mN in the presence and 0.13 mN following pre-incubation with the tyrosine kinase inhibitor Tyrphostin A23 (100 mu M).7 We conclude that ET-1 induced an increase in myofilament calcium sensitivity in rat pulmonary arteries via the activation of ETA receptors and by a mechanism(s) independent of tyrosine kinase.",
keywords = "smooth muscle, pulmonary artery, ET-1, ETA, ETB, calcium sensitization, MYOSIN LIGHT CHAIN, RABBIT MESENTERIC-ARTERY, ENDOTHELIN RECEPTOR, GENE-EXPRESSION, HYPOXIC VASOCONSTRICTION, CONTRACTILE RESPONSE, CA2+ SENSITIVITY, HYPERTENSION, PHOSPHORYLATION, ANTAGONIST",
author = "Evans, {A M} and Cobban, {H J} and Nixon, {G F}",
year = "1999",
language = "English",
volume = "127",
pages = "153--160",
journal = "British Journal of Pharmacology",
issn = "0007-1188",
publisher = "Wiley-Blackwell",

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TY - JOUR

T1 - ETA receptors are the primary mediators of myofilament calcium sensitization induced by ET-1 in rat pulmonary artery smooth muscle: a tyrosine kinase independent pathway

AU - Evans, A M

AU - Cobban, H J

AU - Nixon, G F

PY - 1999

Y1 - 1999

N2 - 1 We have investigated the possibility that ET-1 can induce an increase in myofilament calcium sensitivity in pulmonary artery smooth muscle. Arterial rings were permeabilized using a-toxin (120 mu g ml(-1)), in the presence of A23187 (10 mu M) to 'knock out' Ca2+ stores, and pre-constricted with pCa 6.8 (buffered with 10 mM EGTA). In the presence of this fixed Ca2+ concentration, 1 mu M ET-I induced a sustained, reversible constriction of 0.15 mN.2 Pulmonary arterial rings were freeze-clamped at the peak of the induced constriction (time matched). Subsequent densitometric analysis revealed that ET-I (1 mu M) increased the level of phosphorylated myosin light chains by 34% compared to an 11% increase in the presence of pCa 6.8 alone.3 In contrast to ET-1, the selective ETB receptor agonist Sarafotoxin S6C (100 nh I) failed to induce a significant constriction.4 The constriction induced by 1 mu M ET-I was reversibly inhibited when the preparation was preincubated (15 min) with the ETA receptor antagonist BQ 123 (100 mu M). The constriction measured 0.13 mN in the absence and 0.07 mN in the presence of 100 mu M BQ 123.5 In contrast, the constriction induced by 1 mu M ET-I measured 0.19 mN in the absence and 0.175 mN following a 15 min pre-incubation with the ETB antagonist BQ 788 (100 mu M).6 The constriction induced by 1 mu M ET-I measured 0.14 mN in the presence and 0.13 mN following pre-incubation with the tyrosine kinase inhibitor Tyrphostin A23 (100 mu M).7 We conclude that ET-1 induced an increase in myofilament calcium sensitivity in rat pulmonary arteries via the activation of ETA receptors and by a mechanism(s) independent of tyrosine kinase.

AB - 1 We have investigated the possibility that ET-1 can induce an increase in myofilament calcium sensitivity in pulmonary artery smooth muscle. Arterial rings were permeabilized using a-toxin (120 mu g ml(-1)), in the presence of A23187 (10 mu M) to 'knock out' Ca2+ stores, and pre-constricted with pCa 6.8 (buffered with 10 mM EGTA). In the presence of this fixed Ca2+ concentration, 1 mu M ET-I induced a sustained, reversible constriction of 0.15 mN.2 Pulmonary arterial rings were freeze-clamped at the peak of the induced constriction (time matched). Subsequent densitometric analysis revealed that ET-I (1 mu M) increased the level of phosphorylated myosin light chains by 34% compared to an 11% increase in the presence of pCa 6.8 alone.3 In contrast to ET-1, the selective ETB receptor agonist Sarafotoxin S6C (100 nh I) failed to induce a significant constriction.4 The constriction induced by 1 mu M ET-I was reversibly inhibited when the preparation was preincubated (15 min) with the ETA receptor antagonist BQ 123 (100 mu M). The constriction measured 0.13 mN in the absence and 0.07 mN in the presence of 100 mu M BQ 123.5 In contrast, the constriction induced by 1 mu M ET-I measured 0.19 mN in the absence and 0.175 mN following a 15 min pre-incubation with the ETB antagonist BQ 788 (100 mu M).6 The constriction induced by 1 mu M ET-I measured 0.14 mN in the presence and 0.13 mN following pre-incubation with the tyrosine kinase inhibitor Tyrphostin A23 (100 mu M).7 We conclude that ET-1 induced an increase in myofilament calcium sensitivity in rat pulmonary arteries via the activation of ETA receptors and by a mechanism(s) independent of tyrosine kinase.

KW - smooth muscle

KW - pulmonary artery

KW - ET-1

KW - ETA

KW - ETB

KW - calcium sensitization

KW - MYOSIN LIGHT CHAIN

KW - RABBIT MESENTERIC-ARTERY

KW - ENDOTHELIN RECEPTOR

KW - GENE-EXPRESSION

KW - HYPOXIC VASOCONSTRICTION

KW - CONTRACTILE RESPONSE

KW - CA2+ SENSITIVITY

KW - HYPERTENSION

KW - PHOSPHORYLATION

KW - ANTAGONIST

M3 - Article

VL - 127

SP - 153

EP - 160

JO - British Journal of Pharmacology

JF - British Journal of Pharmacology

SN - 0007-1188

ER -