Increased function of inhibitory neuronal M2 muscarinic receptors in diabetic rat lungs

Kristen E. Belmonte, David Jacoby, Allison Fryer

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

1. The function of inhibitory neuronal M2 muscarinic receptors in diabetic rat lungs was investigated. 2. Neuronal M2 muscarinic receptors inhibit acetylcholine release from parasympathetic nerves. Thus, stimulation of neuronal M2 muscarinic receptors with muscarinic agonists, such as pilocarpine, inhibits acetylcholine release and vagally induced bronchoconstriction. In contrast, blockade of neuronal M2 muscarinic receptors with selective M2 muscarinic antagonists, such as AF-DX 116, potentiates acetylcholine release and vagally induced bronchoconstriction. 3. Rats were made diabetic by streptozotocin (65 mg kg-1, i.v.). After 7-14 days the rats were anaesthetized with urethane (1.5 g kg-1, i.p.), tracheostomized, vagotomized, ventilated and paralysed with suxamethonium (30 mg kg-1, i.v.). Some 7 day diabetic rats were treated with low doses of long acting (NPH) insulin (2 units day-1, s.c.) for 7 days before experimentation. This dose of insulin was not sufficient to restore normoglycaemia in diabetic rats. Thus, insulin-treated diabetic rats remained hyperglycaemic. 4. Distal electrical stimulation (5-70 Hz, 6 s, 40 V, 0.4 ms) of the vagi caused bronchoconstriction, measured as an increase in inflation pressure and bradycardia. In diabetic rats, vagally induced bronchoconstriction was significantly depressed vs controls. In contrast, bronchoconstriction caused by i.v. acetylcholine was similar in diabetic and control animals. 5. The function of neuronal M2 muscarinic receptors was tested with the muscarinic agonist pilocarpine (0.00-100.0 μg kg-1 i.v.) and the antagonist AF-DX 116 (0.01-3.0 mg kg-1, i.v.). Pilocarpine inhibited vagally-induced bronchoconstriction (30 Hz, 20-40 V, 0.4 ms at 6 s) and AF-DX 116 potentiated vagally-induced bronchoconstriction (20 Hz, 20-40 V, 0.4 ms at 6 s) to a significantly greater degree in diabetic rats compared to controls. 6. Both frequency-dependent vagally-induced bronchoconstriction and M2 muscarinic receptor function could be restored to nearly control values in diabetic rats treated with low doses of insulin. 7. Displacement of [3H]QNB (1 nM) with the agonist carbachol (10.0 nM-10.0 mM) from diabetic cardiac M2 muscarinic receptors revealed a half log increase in agonist binding affinity at both the high and low affinity binding sites vs controls. In contrast, M2 receptors from insulin-treated diabetic rat hearts showed no significant difference in binding affinity vs controls. 8. These data show that neuronal M2 muscarinic receptors in the lungs have increased function in diabetic rats, suggesting that insulin modulates M2 muscarinic receptor function.

Original languageEnglish (US)
Pages (from-to)1287-1294
Number of pages8
JournalBritish Journal of Pharmacology
Volume121
Issue number7
DOIs
StatePublished - 1997
Externally publishedYes

Fingerprint

Muscarinic M2 Receptors
Bronchoconstriction
Lung
Pilocarpine
Insulin
Acetylcholine
Muscarinic Agonists
Long-Acting Insulin
Isophane Insulin
Succinylcholine
Muscarinic Antagonists
Urethane
Insulin Receptor
Economic Inflation
Carbachol
Muscarinic Receptors
Bradycardia
Streptozocin
Electric Stimulation

Keywords

  • AF-DX 116
  • Airway responsiveness
  • Diabetes
  • Hypoinsulinaemia
  • Muscarinic receptors
  • Pilocarpine
  • Streptozotocin

ASJC Scopus subject areas

  • Pharmacology

Cite this

Increased function of inhibitory neuronal M2 muscarinic receptors in diabetic rat lungs. / Belmonte, Kristen E.; Jacoby, David; Fryer, Allison.

In: British Journal of Pharmacology, Vol. 121, No. 7, 1997, p. 1287-1294.

Research output: Contribution to journalArticle

@article{09315c88fc2b4c46bbe6cb75908b254a,
title = "Increased function of inhibitory neuronal M2 muscarinic receptors in diabetic rat lungs",
abstract = "1. The function of inhibitory neuronal M2 muscarinic receptors in diabetic rat lungs was investigated. 2. Neuronal M2 muscarinic receptors inhibit acetylcholine release from parasympathetic nerves. Thus, stimulation of neuronal M2 muscarinic receptors with muscarinic agonists, such as pilocarpine, inhibits acetylcholine release and vagally induced bronchoconstriction. In contrast, blockade of neuronal M2 muscarinic receptors with selective M2 muscarinic antagonists, such as AF-DX 116, potentiates acetylcholine release and vagally induced bronchoconstriction. 3. Rats were made diabetic by streptozotocin (65 mg kg-1, i.v.). After 7-14 days the rats were anaesthetized with urethane (1.5 g kg-1, i.p.), tracheostomized, vagotomized, ventilated and paralysed with suxamethonium (30 mg kg-1, i.v.). Some 7 day diabetic rats were treated with low doses of long acting (NPH) insulin (2 units day-1, s.c.) for 7 days before experimentation. This dose of insulin was not sufficient to restore normoglycaemia in diabetic rats. Thus, insulin-treated diabetic rats remained hyperglycaemic. 4. Distal electrical stimulation (5-70 Hz, 6 s, 40 V, 0.4 ms) of the vagi caused bronchoconstriction, measured as an increase in inflation pressure and bradycardia. In diabetic rats, vagally induced bronchoconstriction was significantly depressed vs controls. In contrast, bronchoconstriction caused by i.v. acetylcholine was similar in diabetic and control animals. 5. The function of neuronal M2 muscarinic receptors was tested with the muscarinic agonist pilocarpine (0.00-100.0 μg kg-1 i.v.) and the antagonist AF-DX 116 (0.01-3.0 mg kg-1, i.v.). Pilocarpine inhibited vagally-induced bronchoconstriction (30 Hz, 20-40 V, 0.4 ms at 6 s) and AF-DX 116 potentiated vagally-induced bronchoconstriction (20 Hz, 20-40 V, 0.4 ms at 6 s) to a significantly greater degree in diabetic rats compared to controls. 6. Both frequency-dependent vagally-induced bronchoconstriction and M2 muscarinic receptor function could be restored to nearly control values in diabetic rats treated with low doses of insulin. 7. Displacement of [3H]QNB (1 nM) with the agonist carbachol (10.0 nM-10.0 mM) from diabetic cardiac M2 muscarinic receptors revealed a half log increase in agonist binding affinity at both the high and low affinity binding sites vs controls. In contrast, M2 receptors from insulin-treated diabetic rat hearts showed no significant difference in binding affinity vs controls. 8. These data show that neuronal M2 muscarinic receptors in the lungs have increased function in diabetic rats, suggesting that insulin modulates M2 muscarinic receptor function.",
keywords = "AF-DX 116, Airway responsiveness, Diabetes, Hypoinsulinaemia, Muscarinic receptors, Pilocarpine, Streptozotocin",
author = "Belmonte, {Kristen E.} and David Jacoby and Allison Fryer",
year = "1997",
doi = "10.1038/sj.bjp.0701274",
language = "English (US)",
volume = "121",
pages = "1287--1294",
journal = "British Journal of Pharmacology",
issn = "0007-1188",
publisher = "Wiley-Blackwell",
number = "7",

}

TY - JOUR

T1 - Increased function of inhibitory neuronal M2 muscarinic receptors in diabetic rat lungs

AU - Belmonte, Kristen E.

AU - Jacoby, David

AU - Fryer, Allison

PY - 1997

Y1 - 1997

N2 - 1. The function of inhibitory neuronal M2 muscarinic receptors in diabetic rat lungs was investigated. 2. Neuronal M2 muscarinic receptors inhibit acetylcholine release from parasympathetic nerves. Thus, stimulation of neuronal M2 muscarinic receptors with muscarinic agonists, such as pilocarpine, inhibits acetylcholine release and vagally induced bronchoconstriction. In contrast, blockade of neuronal M2 muscarinic receptors with selective M2 muscarinic antagonists, such as AF-DX 116, potentiates acetylcholine release and vagally induced bronchoconstriction. 3. Rats were made diabetic by streptozotocin (65 mg kg-1, i.v.). After 7-14 days the rats were anaesthetized with urethane (1.5 g kg-1, i.p.), tracheostomized, vagotomized, ventilated and paralysed with suxamethonium (30 mg kg-1, i.v.). Some 7 day diabetic rats were treated with low doses of long acting (NPH) insulin (2 units day-1, s.c.) for 7 days before experimentation. This dose of insulin was not sufficient to restore normoglycaemia in diabetic rats. Thus, insulin-treated diabetic rats remained hyperglycaemic. 4. Distal electrical stimulation (5-70 Hz, 6 s, 40 V, 0.4 ms) of the vagi caused bronchoconstriction, measured as an increase in inflation pressure and bradycardia. In diabetic rats, vagally induced bronchoconstriction was significantly depressed vs controls. In contrast, bronchoconstriction caused by i.v. acetylcholine was similar in diabetic and control animals. 5. The function of neuronal M2 muscarinic receptors was tested with the muscarinic agonist pilocarpine (0.00-100.0 μg kg-1 i.v.) and the antagonist AF-DX 116 (0.01-3.0 mg kg-1, i.v.). Pilocarpine inhibited vagally-induced bronchoconstriction (30 Hz, 20-40 V, 0.4 ms at 6 s) and AF-DX 116 potentiated vagally-induced bronchoconstriction (20 Hz, 20-40 V, 0.4 ms at 6 s) to a significantly greater degree in diabetic rats compared to controls. 6. Both frequency-dependent vagally-induced bronchoconstriction and M2 muscarinic receptor function could be restored to nearly control values in diabetic rats treated with low doses of insulin. 7. Displacement of [3H]QNB (1 nM) with the agonist carbachol (10.0 nM-10.0 mM) from diabetic cardiac M2 muscarinic receptors revealed a half log increase in agonist binding affinity at both the high and low affinity binding sites vs controls. In contrast, M2 receptors from insulin-treated diabetic rat hearts showed no significant difference in binding affinity vs controls. 8. These data show that neuronal M2 muscarinic receptors in the lungs have increased function in diabetic rats, suggesting that insulin modulates M2 muscarinic receptor function.

AB - 1. The function of inhibitory neuronal M2 muscarinic receptors in diabetic rat lungs was investigated. 2. Neuronal M2 muscarinic receptors inhibit acetylcholine release from parasympathetic nerves. Thus, stimulation of neuronal M2 muscarinic receptors with muscarinic agonists, such as pilocarpine, inhibits acetylcholine release and vagally induced bronchoconstriction. In contrast, blockade of neuronal M2 muscarinic receptors with selective M2 muscarinic antagonists, such as AF-DX 116, potentiates acetylcholine release and vagally induced bronchoconstriction. 3. Rats were made diabetic by streptozotocin (65 mg kg-1, i.v.). After 7-14 days the rats were anaesthetized with urethane (1.5 g kg-1, i.p.), tracheostomized, vagotomized, ventilated and paralysed with suxamethonium (30 mg kg-1, i.v.). Some 7 day diabetic rats were treated with low doses of long acting (NPH) insulin (2 units day-1, s.c.) for 7 days before experimentation. This dose of insulin was not sufficient to restore normoglycaemia in diabetic rats. Thus, insulin-treated diabetic rats remained hyperglycaemic. 4. Distal electrical stimulation (5-70 Hz, 6 s, 40 V, 0.4 ms) of the vagi caused bronchoconstriction, measured as an increase in inflation pressure and bradycardia. In diabetic rats, vagally induced bronchoconstriction was significantly depressed vs controls. In contrast, bronchoconstriction caused by i.v. acetylcholine was similar in diabetic and control animals. 5. The function of neuronal M2 muscarinic receptors was tested with the muscarinic agonist pilocarpine (0.00-100.0 μg kg-1 i.v.) and the antagonist AF-DX 116 (0.01-3.0 mg kg-1, i.v.). Pilocarpine inhibited vagally-induced bronchoconstriction (30 Hz, 20-40 V, 0.4 ms at 6 s) and AF-DX 116 potentiated vagally-induced bronchoconstriction (20 Hz, 20-40 V, 0.4 ms at 6 s) to a significantly greater degree in diabetic rats compared to controls. 6. Both frequency-dependent vagally-induced bronchoconstriction and M2 muscarinic receptor function could be restored to nearly control values in diabetic rats treated with low doses of insulin. 7. Displacement of [3H]QNB (1 nM) with the agonist carbachol (10.0 nM-10.0 mM) from diabetic cardiac M2 muscarinic receptors revealed a half log increase in agonist binding affinity at both the high and low affinity binding sites vs controls. In contrast, M2 receptors from insulin-treated diabetic rat hearts showed no significant difference in binding affinity vs controls. 8. These data show that neuronal M2 muscarinic receptors in the lungs have increased function in diabetic rats, suggesting that insulin modulates M2 muscarinic receptor function.

KW - AF-DX 116

KW - Airway responsiveness

KW - Diabetes

KW - Hypoinsulinaemia

KW - Muscarinic receptors

KW - Pilocarpine

KW - Streptozotocin

UR - http://www.scopus.com/inward/record.url?scp=0030838507&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0030838507&partnerID=8YFLogxK

U2 - 10.1038/sj.bjp.0701274

DO - 10.1038/sj.bjp.0701274

M3 - Article

C2 - 9257905

AN - SCOPUS:0030838507

VL - 121

SP - 1287

EP - 1294

JO - British Journal of Pharmacology

JF - British Journal of Pharmacology

SN - 0007-1188

IS - 7

ER -