Abstract：
:Hypothermia increases the sensitivity of isolated cardiac muscle to stimulation by beta-adrenoceptor agonists. The purpose of this study was to determine pharmacologically whether this supersensitivity is associated with a change in the affinity of agonists for the receptor. The positive inotropic and chronotropic responses of guinea-pig paced left and spontaneously beating right atria were recorded. Cumulative dose--response curves to noradrenaline (or adrenaline) were compared with isoproterenol in each tissue. At 38 degrees C, the rate curves were to the left of the tension curves, with lower mean effective concentration (EC50) values. However, this difference was less for noradrenaline and adrenaline which were therefore tension selective relative to isoproterenol. Lowering the temperature to 25 degrees C induced supersensitivity, all dose--response curves being displaced to the left. In the presence of carbachol the curves were shifted to the right with depression of the maxima. Dissociation constants (KA) were calculated from plots of reciprocals of equiactive concentrations obtained before and in the presence of carbachol. KA values for rate and tension responses of each agonist were identical at 38 degrees C, indicating that the rate selectivity was not due to affinity differences. The efficacies (er) of noradrenaline and adrenaline were greater than isoproterenol for tension, but smaller for rate responses, which may explain their relative tension selectivity. At 25 degrees C, the KA values of all agonists were reduced approximately 10-fold. Hypothermia-induced supersensitivity is therefore associated with an increase in affinity for the cardiac beta-adrenoceptor.
journal_name
Can J Physiol Pharmacoljournal_title
Canadian journal of physiology and pharmacologyauthors
Broadley KJ,McNeill JHdoi
10.1139/y83-088subject
Has Abstractpub_date
1983-06-01 00:00:00pages
572-80issue
6eissn
0008-4212issn
1205-7541journal_volume
61pub_type
杂志文章abstract：:Most physiological and pathophysiological responses to bradykinin are mediated by G-protein-coupled receptors designated B2 receptors. Discovery of antagonists for these receptors has brought about a revolution in research in the kinin field. The chemistry and development of antagonists for B2 kinin receptors are disc...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章,评审
doi：10.1139/y95-106
更新日期：1995-07-01 00:00:00
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journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y04-034
更新日期：2004-05-01 00:00:00
abstract：:Cumulative data suggest the significant role of the renin-angiotensin system in the development of the pathological consequences of diabetes mellitus (DM). Newly synthesized AT2 receptor agonists gained importance as a target for creating new antihypertensives. The aim of the present work was to study the effects of p...
journal_title：Canadian journal of physiology and pharmacology
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journal_title：Canadian journal of physiology and pharmacology
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doi：
更新日期：1997-08-01 00:00:00
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journal_title：Canadian journal of physiology and pharmacology
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doi：10.1139/y76-074
更新日期：1976-08-01 00:00:00
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journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章,评审
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更新日期：2010-05-01 00:00:00
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journal_title：Canadian journal of physiology and pharmacology
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doi：10.1139/y86-215
更新日期：1986-10-01 00:00:00
abstract：:The threshold for electrically induced ventricular fibrillation was determined in anesthetized open-chest dogs, before and after blockade of atrioventricular (A-V) conduction. Without exception, the threshold was significantly elevated after creation of the block. The precise mechanism of this effect is not known at t...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y83-160
更新日期：1983-09-01 00:00:00
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pub_type： 杂志文章,评审
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更新日期：2012-06-01 00:00:00
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journal_title：Canadian journal of physiology and pharmacology
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doi：
更新日期：2001-01-01 00:00:00
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journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y03-091
更新日期：2003-10-01 00:00:00
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journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/cjpp-2017-0228
更新日期：2018-01-01 00:00:00
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journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y89-014
更新日期：1989-01-01 00:00:00
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journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y92-199
更新日期：1992-10-01 00:00:00
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journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y95-090
更新日期：1995-06-01 00:00:00
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journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y80-218
更新日期：1980-12-01 00:00:00
abstract：:The effect of chronic consumption of diets containing either different sources of dietary fibre (8% guar, 8% pectin, or 8% multifibre) or low carbohydrate upon carbohydrate tolerance was examined in rats. Weight gain was significantly lower throughout the entire 28-day study period with the guar group and after 20 day...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y82-107
更新日期：1982-06-01 00:00:00
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journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y94-150
更新日期：1994-09-01 00:00:00
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journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y02-033
更新日期：2002-04-01 00:00:00
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journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/cjpp-2014-0477
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journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章,评审
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更新日期：2003-02-01 00:00:00
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journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章,评审
doi：10.1139/y2012-073
更新日期：2012-06-01 00:00:00
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journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y91-110
更新日期：1991-06-01 00:00:00
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journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y78-061
更新日期：1978-06-01 00:00:00
abstract：:Delta 9-Tetrahydrocannabinol (20 mg/kg i.p.) and propranolol (20 and 50 mg/kg i.p.) produced marked falls in the rectal temperatures of mice kept at an ambient temperature of 22 degrees C. Propranolol (50 mg/kg i.p.) also decreased the thermogenic activity of brown fat, as measured by a decrease in the level of [3H]GD...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y91-114
更新日期：1991-06-01 00:00:00
abstract：:The mechanism whereby chronic rapid ventricular pacing induces severe heart failure is unclear, but the phenomenon is associated with a reduction in left ventricular ATP levels. Accordingly, the current study was undertaken to evaluate the acute effects of rapid ventricular pacing on hemodynamics, left ventricular ade...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y94-002
更新日期：1994-01-01 00:00:00
abstract：:In hypertension, the relationship between atrial natriuretic peptide (ANP) and vasopressin (AVP) is not yet clear, although their renal actions are effectively autoregulation. To examine the possible interaction further, the responses to ANP infusion (75 ng x min (-1), i.v.) have been investigated in both hypertensive...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：
更新日期：1999-02-01 00:00:00
abstract：:Female rats subjected to 48 h of water deprivation drank more than similarly deprived males. There was no sexual difference in the dipsogenic responses to intracellular dehydration produced by intravenous hypertonic NaCl but females drank considerably more than males in response to the extracellular stimuli of hyperon...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y80-179
更新日期：1980-10-01 00:00:00
abstract：:The world-wide increase in cancer incidence imposes a corresponding significant increase in the use of chemotherapeutic agents. Nephrotoxicity is a side effect frequently encountered with cyclophosphamide (CP), which is also well-known to cause acute and chronic lung toxicities. The current study focuses on the evalua...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/cjpp-2015-0070
更新日期：2016-04-01 00:00:00
abstract：:Amiodarone is a new antiarrhythmic drug, commonly coadministered with digoxin in various cardiac disorders. Amiodarone caused a 10-fold increase of serum digoxin in rats, when the two drugs were simultaneously administered. Amiodarone significantly reduced digoxin uptake by renal cortical slices in the rat, and failed...
journal_title：Canadian journal of physiology and pharmacology
pub_type： 杂志文章
doi：10.1139/y83-212
更新日期：1983-12-01 00:00:00
