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The effects of changes in coronary blood flow and coronary artery pressure on left ventricular (LV) contractility were determined in 18 animals. Dogs on cardiopulmonary bypass provided isovolumetric LV contractions during controlled perfusion of the coronary circulation. Coronary venous efflux, myocardial oxygen consumption, peak LV pressure, LV dp/dt, and the forcevelocity relations of the LV were determined at normal and at "supernormal" levels of flow and pressure. Coronary vasodilatation was obtained with nitroglycerine, permitting independent variation of flow and pressure. Augmenting flow by increasing pressure increased LV contractility, as reflected by increases in peak LV pressure, dp/dt max, peak wall tension, and maximal measured contractile element velocity. Increased contractility appeared to be primarily due to increased flow, rather than to pressure, as an increase in flow without an increase in pressure produced similar changes, and decreases in pressure at constant flow did not change maximal measured contractile element velocity or dp/dt max, although some decrease in peak LV pressure and wall tension did occur. These data suggest that coronary flow is an independent determinant of the contractile state of myocardium, and that an increase in flow in excess of that required to supply metabolic demands augments myocardial contractility. ADDITIONAL KEY WORDSmyocardial contractility nitroglycerine coronary vascular resistance myocardial oxygen consumption contractile element velocity force-velocity relations inotropic state ventricular compliance• The relationships between ventricular work, coronary blood flow and myocardial oxygen consumption (MVo 2 ) are well established (1). Ventricular contractility, as assessed by developed wall tension and the rate of contractile element shortening, has been shown to be an important determinant of MVo 2 and coronary vascular resistance (2, 3). The converse causal relationship (viz., coronary blood flow as a determinant of contractility), however, has not been established. Gregg (4, 5) observed that a change in left circumflex artery perfusion pressure caused directional changes in both coronary flow and MV02 without consistent changes in heartFrom the Clinic of Surgery, National Heart and Lung Institute, Bethesda, Maryland 20014.Received April 2, 1970; accepted for publication October 19, 1970. rate, cardiac output, aortic pressure, or left ventricular end-diastolic pressure (LV, EDP). "Gregg's phenomenon" or the suggestion that coronary flow and coronary artery pressure (CAP) were independent determinants of MV02 and ventricular contractility has been investigated in several laboratories by a variety of experimental methods (6-9). The results of these studies have been the subject of controversy possibly related to the variety of preparations utilized, amount of myocardial work generated in these studies and the failure to differentiate between the effects produced by changes in coronary flow versus coronary artery pressure. The present studies we...

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SUMMARYTwenty-two patients underwent cardiac catheterization before and an average of five months after aorto-coronary bypass operation (ACBO). Two groups were examined: 10 patients with all grafts patent, and 12 patients with one or more grafts occluded. All patients improved symptomatically, regardless of graft patency. However, in the occluded group, left ventricular enddiastolic pressure (LVEDP) increased (4.4 + 2.2 mm Hg, P < 0.05), stroke volume index fell (9.8 + 3.1 ml/m2, P <0.05), ejection fraction decreased (10 + 4%, P <0.05), and left ventricular stroke work index fell (12 + 3 g-m/m2, P < 0.01).Qualitative

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Salt stress is one of the most common stresses in agricultural regions worldwide. In particular, sugarcane is affected by salt stress conditions, and no sugarcane cultivar presently show high productivity accompanied by a tolerance to salt stress. Proteomic analysis allows elucidation of the important pathways involved in responses to various abiotic stresses at the biochemical and molecular levels. Thus, this study aimed to analyse the proteomic effects of salt stress in micropropagated shoots of two sugarcane cultivars (CB38-22 and RB855536) using a label-free proteomic approach. The mass spectrometry proteomics data are available via ProteomeXchange with identifier PXD006075. The RB855536 cultivar is more tolerant to salt stress than CB38-22. A quantitative label-free shotgun proteomic analysis identified 1172 non-redundant proteins, and 1160 of these were observed in both cultivars in the presence or absence of NaCl. Compared with CB38-22, the RB855536 cultivar showed a greater abundance of proteins involved in non-enzymatic antioxidant mechanisms, ion transport, and photosynthesis. Some proteins, such as calcium-dependent protein kinase, photosystem I, phospholipase D, and glyceraldehyde-3-phosphate dehydrogenase, were more abundant in the RB855536 cultivar under salt stress. Our results provide new insights into the response of sugarcane to salt stress, and the changes in the abundance of these proteins might be important for the acquisition of ionic and osmotic homeostasis during exposure to salt stress.