Increased calcium influx mediates increased cardiac stiffness in hyperthyroid rats

Levick, Scott, Fenning, Andrew and Brown, Lindsay (2005) Increased calcium influx mediates increased cardiac stiffness in hyperthyroid rats. Cell Biochemistry and Biophysics, 43 1: 53-60. doi:10.1385/CBB:43:1:053

Author Levick, Scott
Fenning, Andrew
Brown, Lindsay
Title Increased calcium influx mediates increased cardiac stiffness in hyperthyroid rats
Journal name Cell Biochemistry and Biophysics   Check publisher's open access policy
ISSN 1085-9195
Publication date 2005-08
Sub-type Article (original research)
DOI 10.1385/CBB:43:1:053
Volume 43
Issue 1
Start page 53
End page 60
Total pages 8
Place of publication Totowa, NJ, United States
Publisher Humana Press
Collection year 2005
Language eng
Subject C1
320502 Basic Pharmacology
730106 Cardiovascular system and diseases
Abstract Cardiac remodeling (hypertrophy and fibrosis) and an increased left ventricular diastolic stiffness characterize models of hypertension such as the SHR and DOCA-salt hypertensive rats. By contrast, hyperthyroidism induces hypertrophy and hypertension, yet collagen expression and deposition is unchanged or decreased, whereas diastolic stiffness is increased. We determined the possible role of increased calcium influx in the development of increased diastolic stiffness in hyperthyroidism by administering verapamil (15 mg/[kg(.)d] orally) to rats given triiodothyronine (T-3) (0.5 mg/[kg.d] subcutaneously for 14 d). Administration of T3 significantly increased body temperature (control: 36.7 +/- 0.2 degrees C; T-3: 39.6 +/- 0.2 degrees C), left ventricular wet weight (control: 2.09 +/- 0.02 mg/kg; T-3 3.07 +/- 0.07 mg/kg), systolic blood pressure (control: 128 +/- 5 mmHg; T-3: 156 +/- 4 mmHg), and left ventricular diastolic stiffness (control: 20.6 +/- 2.0; T-3: 28.8 +/- 1.4). Collagen content of the left ventricle was unchanged. Contractile response to noradrenaline in thoracic aortic rings was reduced. Relaxation in response to acetylcholine (ACh) was also reduced in T-3-treated rats, whereas sodium nitroprusside response was unchanged. Verapamil treatment of hyperthyroid rats completely prevented the increased diastolic stiffness and systolic blood pressure while attenuating the increased body temperature and left ventricular weight; collagen content remained unchanged. ACh response in thoracic aortic rings was restored by verapamil. Thus, in hyperthyroid rats, an increased calcium influx is a potential mediator of the increased diastolic stiffness independent of changes in collagen.
Keyword Calcium
Diastolic stiffness
Endothelial dysfunction
Q-Index Code C1
Q-Index Status Provisional Code

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Created: Wed, 15 Aug 2007, 05:56:53 EST