Right ventricular papillary muscles from hyperthyroid and normal cats were studied in vitro at 30°C, at contraction frequencies of 12, 30 and 60/min. At 12/min the contractility of hyperthyroid muscles was significantly greater than normal, as indicated by greater velocity of isotonic shortening, isometric tension development, and rate of tension development. Isotonically contracted muscle leng...

P-glycoprotein (Pgp) is expressed in various normal tissues and plays an important role in drug absorption and disposition. In addition, it is supposed that alterations in the expression levels of Pgp are involved in the inter- and intraindividual variability of pharmacokinetics of many drugs. Since pharmacokinetic properties of various drugs are altered in patients with thyroid disorders, we e...

BACKGROUND Hyperthyroidism is associated with high incidence of thyroid carcinoma; furthermore, tumors arisen in hyperthyroid tissue show an aggressive behavior. Thyroid Stimulating Hormone (TSH) and Thyroid-stimulating antibodies, present in Graves's disease, seem to play a key role in carcinogenesis and tumoral growth. METHODS We retrospectively reviewed our series of patients who underwent...

This study aimed to investigate the relationship between the expression and distribution of myocardial connexin 43 (Cx43) in the left ventricle and the incidence of sudden death due to hyperthyroid heart disease. Total 27 autopsy cases were selected from the Pathology Department of Medical School, Yangtze University from 2009 to 2014. The cases were divided into three groups (n=9): Experimental...

This study investigated the effects of l-thyroxine-induced hyperthyroidism on Ca(2+)/calmodulin (CaM)-dependent protein kinase (CaM kinase II)-mediated sarcoplasmic reticulum (SR) protein phosphorylation, SR Ca(2+) pump (Ca(2+)-ATPase) activity, and contraction duration in slow-twitch soleus muscle of the rabbit. Phosphorylation of Ca(2+)-ATPase and phospholamban (PLN) by endogenous CaM kinase ...

We assessed the frequency and clinical background of normal concentrations of serum total thyroxin (T4) found among 84 hyperthyroid patients out of 633 consecutive patients evaluated for suspected hyperthyroidism. Patients were categorized as having hyperthyroidism if they had hyperthyroid symptoms and signs, had a serum thyrotropin (TSH) 0.1 milli-int. unitJL as measured by immuneradiometric a...

Both systolic pressure-volume area (PVA) and force-time integral (FM1) have been used as measures of oxygen consumption per beat (Vo2) in the isolated left ventricle. The reciprocal of the slope of the Vo2-PVA relation has been considered to reflect the chemomechanical energy transduction efficiency of the contractile machinery (contractile efficiency), whereas its Vo2 intercept consists of ene...

Both systolic pressure-volume area (PVA) and force-time integral (FTI) have been used as measures of oxygen consumption per beat (VO2) in the isolated left ventricle. The reciprocal of the slope of the VO2-PVA relation has been considered to reflect the chemomechanical energy transduction efficiency of the contractile machinery (contractile efficiency), whereas its VO2 intercept consists of ene...

The ability of 10 muM epinephrine or isoproterenol to stimulate cyclic AMP accumulation was decreased in hepatocytes isolated from hyperthyroid (triiodothyronine treated) as compared to euthyroid rats. In the presence of methylisobutylxanthine, epinephrine or isoproterenol-stimulated cyclic AMP accumulation was approximately 65% lower in hyperthyroid as compared with euthyroid rat hepatocytes. ...