Adrenergic receptors of isolated snake atria

K. W. Chiu, James Sham

Research output: Contribution to journalArticle

Abstract

1. 1. Cardiac adrenergic receptors in snakes were examined using an isolated atria preparation of Naja naja and Ptyas korros. Treatments included an examination of the atrial responses to selective α- and β-adrenergic agonists and antagonists. 2. 2. In both species, both phenylephrine and isoproterenol produced dose-dependent increases in the atrial beating rate and tension. Phenylephrine-induced increases were characterized with a high affinity and low affinity components. 3. 3. These positive chronotropic and inotropic effects produced by phenylephrine and isoproterenol were abolished with propranolol and in the phenylephrine-induced response phentolamine also attenuated the low affinity response and blocked the high affinity response. 4. 4. With catecholamines depletion via 6-OH dopamine or reserpine, the high affinity component in the phenylephrine-induced response was no longer observed. 5. 5. It is concluded that β-adrenoceptors are the predominant post-synaptic adrenoceptors in snake atria. Stimulatory presynaptic α-adrenoceptors for modulating noradrenaline release may also be present.

Original languageEnglish (US)
Pages (from-to)445-450
Number of pages6
JournalComparative Biochemistry and Physiology. Part C, Comparative
Volume81
Issue number2
DOIs
StatePublished - 1985
Externally publishedYes

Fingerprint

Snakes
Phenylephrine
Adrenergic Receptors
Isoproterenol
Elapidae
Adrenergic Agonists
Adrenergic Antagonists
Phentolamine
Reserpine
Propranolol
Catecholamines
Dopamine
Norepinephrine

ASJC Scopus subject areas

  • Immunology
  • Pharmacology

Cite this

Adrenergic receptors of isolated snake atria. / Chiu, K. W.; Sham, James.

In: Comparative Biochemistry and Physiology. Part C, Comparative, Vol. 81, No. 2, 1985, p. 445-450.

Research output: Contribution to journalArticle

@article{b0c156b1e6c14912854c58b6f475a52b,
title = "Adrenergic receptors of isolated snake atria",
abstract = "1. 1. Cardiac adrenergic receptors in snakes were examined using an isolated atria preparation of Naja naja and Ptyas korros. Treatments included an examination of the atrial responses to selective α- and β-adrenergic agonists and antagonists. 2. 2. In both species, both phenylephrine and isoproterenol produced dose-dependent increases in the atrial beating rate and tension. Phenylephrine-induced increases were characterized with a high affinity and low affinity components. 3. 3. These positive chronotropic and inotropic effects produced by phenylephrine and isoproterenol were abolished with propranolol and in the phenylephrine-induced response phentolamine also attenuated the low affinity response and blocked the high affinity response. 4. 4. With catecholamines depletion via 6-OH dopamine or reserpine, the high affinity component in the phenylephrine-induced response was no longer observed. 5. 5. It is concluded that β-adrenoceptors are the predominant post-synaptic adrenoceptors in snake atria. Stimulatory presynaptic α-adrenoceptors for modulating noradrenaline release may also be present.",
author = "Chiu, {K. W.} and James Sham",
year = "1985",
doi = "10.1016/0742-8413(85)90035-0",
language = "English (US)",
volume = "81",
pages = "445--450",
journal = "Comparative biochemistry and physiology. C: Comparative pharmacology",
issn = "0306-4492",
publisher = "Elsevier BV",
number = "2",

}

TY - JOUR

T1 - Adrenergic receptors of isolated snake atria

AU - Chiu, K. W.

AU - Sham, James

PY - 1985

Y1 - 1985

N2 - 1. 1. Cardiac adrenergic receptors in snakes were examined using an isolated atria preparation of Naja naja and Ptyas korros. Treatments included an examination of the atrial responses to selective α- and β-adrenergic agonists and antagonists. 2. 2. In both species, both phenylephrine and isoproterenol produced dose-dependent increases in the atrial beating rate and tension. Phenylephrine-induced increases were characterized with a high affinity and low affinity components. 3. 3. These positive chronotropic and inotropic effects produced by phenylephrine and isoproterenol were abolished with propranolol and in the phenylephrine-induced response phentolamine also attenuated the low affinity response and blocked the high affinity response. 4. 4. With catecholamines depletion via 6-OH dopamine or reserpine, the high affinity component in the phenylephrine-induced response was no longer observed. 5. 5. It is concluded that β-adrenoceptors are the predominant post-synaptic adrenoceptors in snake atria. Stimulatory presynaptic α-adrenoceptors for modulating noradrenaline release may also be present.

AB - 1. 1. Cardiac adrenergic receptors in snakes were examined using an isolated atria preparation of Naja naja and Ptyas korros. Treatments included an examination of the atrial responses to selective α- and β-adrenergic agonists and antagonists. 2. 2. In both species, both phenylephrine and isoproterenol produced dose-dependent increases in the atrial beating rate and tension. Phenylephrine-induced increases were characterized with a high affinity and low affinity components. 3. 3. These positive chronotropic and inotropic effects produced by phenylephrine and isoproterenol were abolished with propranolol and in the phenylephrine-induced response phentolamine also attenuated the low affinity response and blocked the high affinity response. 4. 4. With catecholamines depletion via 6-OH dopamine or reserpine, the high affinity component in the phenylephrine-induced response was no longer observed. 5. 5. It is concluded that β-adrenoceptors are the predominant post-synaptic adrenoceptors in snake atria. Stimulatory presynaptic α-adrenoceptors for modulating noradrenaline release may also be present.

UR - http://www.scopus.com/inward/record.url?scp=0021797389&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0021797389&partnerID=8YFLogxK

U2 - 10.1016/0742-8413(85)90035-0

DO - 10.1016/0742-8413(85)90035-0

M3 - Article

C2 - 2861969

AN - SCOPUS:0021797389

VL - 81

SP - 445

EP - 450

JO - Comparative biochemistry and physiology. C: Comparative pharmacology

JF - Comparative biochemistry and physiology. C: Comparative pharmacology

SN - 0306-4492

IS - 2

ER -