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A study was conducted to test whether the production of endothelin-1 in hearts is changed by prolonged exercise in rats. The left ventricle and lungs were homogenized with a Polytron homogenizer for 60 seconds. Reverse transcription polymerase chain reaction was then carried out to determine the expression of prepro-endothelin-1 mRNA. Results indicated that the production of endothelin-1 was significantly increased in the heart by exercise without alterations in endothelin-converting enzyme and receptor expression.

Uterine smooth muscle preparations from pregnant humans were analyzed to determine the alterations in endothelin-1 (ET-1)-induced contraction, ET receptors and receptor subtypes due to pregnancy. Analysis of human uterine membrane preparations from gravid humans indicated the presence of increased ET-1-induced uterine contractions that was attenuated by ETA receptor antagonist. ET-1-induced contractions were also mediated by increased ETA receptors and reduced ETB receptors in pregnant human uterus.

The ET(sub A)- and ET(sub B)-receptor systems are greatly accelerated in the failing heart of rats with chronic heart failure (CHF). This was the main finding in a study that sought to determine the details of the ET system in the failing heart of rats with CHF due to myocardial infarction. Details observed include the markedly higher mRNA level of preproET-1 and the peptide level of ET-1 in the failing heart of rats with CHF than control rats, as well as the equivalent level of ECE-1 mRNA in the two groups. The upregulation of ACE mRNA in the failing heart was also observed

The existence of decreased aortic compliance due to arteriosclerosis has been documented in patients with coronary artery disease. The aim of this study was to investigate the effects of decreased aortic compliance on coronary artery disease. Methods: To simulate coronary artery disease, a fixed stenosis was made in the left circumflex coronary artery in dogs. Ten anaesthetised open chest dogs were used. Aortic compliance was decreased by banding the thoracic aorta with adjustable plastic rings. The level of coronary stenosis was adjusted to reduce the baseline flow by no more than 10% but enough to eliminate reactive hyperaemia induced by a 10 s occlusion. Measurements of haemodynamics, regional myocardial segment length, subendocardial ECG, and myocardial tissue PO2 were performed at five stages (initial control stage, rest and pacing stages without aortic banding, and rest and pacing stages with the aortic banding). Results: Haemodynamic variables were not changed at any stage, except for increased pulse pressure secondary to the aortic banding. During pacing with aortic banding, subendocardial PO2 (Endo) levels were decreased, and subepicardial PO2 (Epi) levels were increased, compared to those without the aortic banding [Endo: 43.2(SD 9.8) v 36.8(10.0) mm Hg, p<0.05; Epi: 34.0(11.5) v 44.4(7.9) mm Hg, p<0.05]. ST elevation on the subendocardial ECG was greater, and myocardial segment shortening was less with the aortic bandage during pacing. Conclusions: .When the work of the heart is increased, a decrease in aortic compliance tends to compromise ischaemic myocardium further in the presence of an induced stenosis of a major coronary artery.Cardiovascular Research 1992;26:1212-1218 [ABSTRACT FROM PUBLISHER]

Study objective – The aim was to examine whether regional myocardial dysfunction has a significant effect on the wall motion and blood flow in remote non-ischaemic regions.Design – Two different severities of regional dysfunction were produced by occluding the left anterior descending coronary artery and perfusing it with a hypoxic solution. Haemodynamic variables were otherwise identical in the two conditions. The relationship of regional dysfunction in the left anterior descending artery region to regional wall motion and regional myocardial blood flow in the left circumflex artery region were examined.Experimental material – 22 anaesthetised mongrel dogs, 9-16 kg, were used for the studies: 14 for the regional wall motion studies, and eight for the regional myocardial blood flow studies.Measurements and main results – Segment shortening in the left anterior descending artery region was impaired differently in the two conditions: arterial occlusion caused a bulge, while hypoxic perfusion caused only mild hypokinesis. Segment shortening and the myocardial blood flow in the left circumflex artery region were augmented similarly in the two conditions. Left ventricular end diastolic pressure and end diastolic segment length in the left circumflex region were increased and aortic pressure was slightly decreased by left anterior descending artery occlusion and hypoxic perfusion, but there was no significant difference between the two conditions. Heart rate was not affected.Conclusion – The augmentation of wall motion and blood flow of the remote myocardium does not depend on the magnitude of acutely induced regional dysfunction per se. The augmented wall motion in the remote region is unlikely to be due to mechanical unloading of the remote myocardium due to an intraventricular regional interaction, but rather to the Frank-Starling mechanism and left ventricular afterload reduction following acute ischaemia. [ABSTRACT FROM PUBLISHER]

For quantitative estimation of ischemia, ECG-synchronized digital subtraction angiography was performed for selective coronary arteriography. The authors obtained sequential myocardial perfusion images at the arterial, capillary, and venous phases. Profile densitometry was performed along the cross section perpendicular to the long axis of the left ventricle to assess regional myocardial perfusion at the capillary phase quantitatively. By this densitometry, the volumes of vascular bed perfused by the left coronary artery could be estimated, and further, nontransmural myocardial infarction could be differentiated from transmural myocardial infarction through the profile of its density curve. This method appears to be useful for the analysis of myocardial perfusion of ischemic heart disease. [ABSTRACT FROM AUTHOR]

A 50-year-old woman with Wolff-Parkinson-White (WPW) syndrome presented with unusual electrocardiographic (ECG) findings following the termination of paroxysmal supraventricular tachycardia. The ECG showed three different QRS complexes and irregular H-R intervals. These QRS complexes consisted of: (1) narrow QRS; (2) wide QRS with delta wave; and (3} wide QRS with left bundle branch block (LBBB). The mechanisms of these findings, revealed by electrophysiological study, were; (1) intermittent anterograde left-sided accessory pathway conduction; (2) rate-dependent ipsilateral LBBB; and (3) intermittent retrogradely conducted atrial echoes that occurred due to intraventricular conduction delay resulting from LBBR. Cases of WPW syndrome with these unusual ECG findings, which were clearly interpreted by electrophysiological study, are rare. [ABSTRACT FROM AUTHOR]

In the unanaesthetized dog propranolol 1 mg/kg intravenously failed to alter significantly coronary or systemic haemodynamics. These results suggest that in the supine, unanaesthetized dog, β-adrenergic receptor activity is minimal in the coronary arteries. [ABSTRACT FROM PUBLISHER]