Effect of low thyroid function on cardiac structure and function in spontaneously hypertensive heart failure rats.
BACKGROUND
Although low thyroid function is known to have detrimental effects on the cardiovascular system, including microvascular impairment, little is known about the pathophysiologic consequences of hypothyroidism in the background of hypertension.


RESULTS
Hypothyroidism was induced in female spontaneously hypertensive heart failure (SHHF) rats by treatment with propylthiouracil (PTU) for 6 months. Untreated SHHF and normotensive Wistar Furth (WF) rats served as controls. In terminal experiments, heart weight, echocardiographic measurements, hemodynamics, and arteriolar morphometry were performed. Left ventricular internal diameter in systole and diastole were increased and wall thickness, ejection fraction, heart rate, systolic blood pressure, and +/-dP/dt were significantly decreased in the treatment group. Surprisingly, there were no observed differences in arteriolar density among the 3 groups.


CONCLUSIONS
As expected, PTU treatment of SHHF rats led to systolic dysfunction and chamber dilation. However, PTU treatment did not lead to arteriolar loss as previously observed in normotensive rats treated with PTU. These finding suggest that induced hypothyroidism leads to detrimental changes in SHHF rats, but the overall effects were no worse than those previously observed in normotensive rats treated with PTU.
Kisso
Bassel
B
Cardiovascular Research Institute, Sanford Research/University of South Dakota, 1100 East 21st Street, Sioux Falls, SD 57105, USA.
Patel
Ankit
A
Redetzke
Rebecca
R
Gerdes
A Martin
AM
D000818:Animals; D005260:Female; D006333:Heart Failure / Q000503:physiopathology*; D006439:Hemodynamics; D006973:Hypertension / Q000503:physiopathology*; D006980:Hyperthyroidism / Q000473:pathology / Q000503:physiopathology*; D008833:Microcirculation; D009206:Myocardium / Q000473:pathology*; D011441:Propylthiouracil / Q000031:analogs & derivatives / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D013961:Thyroid Gland / Q000473:pathology*; D013997:Time Factors
D011441:Propylthiouracil