The present work aims to study the interactive effect of drought stress and high vapour pressure deficit (VPD) on leaf gas exchange, and especially on mesophyll conductance to CO₂ (g_m), in two woody species of great agronomical importance in the Mediterranean basin: Vitis vinifera L. cv. Tempranillo and Olea europaea L. cv. Manzanilla. Plants were grown in specially designed outdoor chambers with ambient and below ambient VPD, under both well-irrigated and drought conditions. g_m was estimated by the variable J method from simultaneous measurements of gas exchange and fluorescence. In both species, the response to soil water deficit was larger in g_s than in g_m, and more important than the response to VPD. Olea europaea was apparently more sensitive to VPD, so that plants growing in more humid chambers showed higher g_s and g_m. In V. vinifera, in contrast, soil water deficit dominated the response of g_s and g_m. Consequently, changes in g_m/g_s were more related to VPD in O. europaea and to soil water deficit in V. vinifera. Most of the limitations of photosynthesis were diffusional and especially due to stomatal closure. No biochemical limitation was detected. The results showed that structural parameters played an important role in determining g_m during the acclimation process. Although the relationship between leaf mass per unit area (M_A) with g_m was scattered, it imposed a limitation to the maximum g_m achievable, with higher values of M_A in O. europaea at lower g_m values. M_A decreased under water stress in O. europaea but it increased in V. vinifera. This resulted in a negative relationship between M_A and the CO₂ draw-down between substomatal cavities and chloroplasts in O. europaea, while being positive in V. vinifera.

Background—: Abnormal left ventricular (LV) deformational mechanics have been demonstrated in patients with hypertrophic cardiomyopathy (HCM) at rest, but there is a lack of information on their adaptation to exercise. The aim of this study was to assess the adaptability of LV strains and torsional mechanics during exercise in HCM patients. Methods and Results—: Twenty nonobstructive HCM patients (age, 48.3±12.3 years; 14 men) and 20 control subjects underwent speckle-tracking echocardiographic measurement of longitudinal, radial, and circumferential strains, systolic twist, and diastolic untwisting rate (UTR) at rest and submaximal exercise. HCM patients showed lower resting longitudinal (−15.7±5.0% versus −19.4±2.6%, P <0.001) and radial (38.1±11.3% versus 44.7±14.4%, P <0.05) strains but higher circumferential strain (−21.9±4.0% versus −18.8±2.3%, P <0.05) and twist (15.7±3.6° versus 9.3±2.6°, P <0.0001) than control subjects. Exercise induced an increase in all strains in control subjects but only a moderate increase in longitudinal strain (to −18.4±5.0%), without significant changes in radial and circumferential strains or twist in HCM patients. Exercise peak UTR was lower (−119.0±31.5°/s versus −137.3±41.1°/s) and occurred later (137±18% versus 125±11% systolic time, P <0.05) in HCM than in control subjects. A significant relationship between twist and UTR was obtained in control subjects (ß=−0.0807, P <0.001) but not in HCM patients (ß=−0.0051, P =0.68). Conclusions—: HCM patients had severely limited strain adaptability and no LV twisting reserve at exercise. They had reduced and delayed UTR with reduced systolic-diastolic coupling efficiency by twist-untwist mechanics.