26This study addressed the hypothesis that long-term deficiency of ovarian hormones,

Key points During compensated hypertrophy in vivo fractional shortening (FS) remains constant until heart failure (HF) develops, when FS decreases from 70% to 39%. Compensated hypertrophy is accompanied by an increase in INa,late and a decrease in Na+,K+‐ATPase current. These changes persist as HF develops. SR Ca2+ content increases during compensated hypertrophy then decreases in HF. In healthy cells, increases in SR Ca2+ content and Ca2+ transients can be achieved by the same amount of inhibition of the Na+,K+‐ATPase as measured in the diseased cells. SERCA function remains constant during compensated hypertrophy then decreases in HF, when there is also an increase in spark frequency and spark‐mediated Ca2+ leak. We suggest an increase in INa,late and a decrease in Na+,K+‐ATPase current and function alters the balance of Ca2+ flux mediated by the Na+/Ca2+ exchange that limits early contractile impairment. Abstract We followed changes in cardiac myocyte Ca2+ and Na+ regulation from the formation of compensated hypertrophy (CH) until signs of heart failure (HF) are apparent using a trans‐aortic pressure overload (TAC) model. In this model, in vivo fractional shortening (FS) remained constant despite HW:BW ratio increasing by 39% (CH) until HF developed 150 days post‐TAC when FS decreased from 70% to 39%. Using live and fixed fluorescence imaging and electrophysiological techniques, we found an increase in INa,late from –0.34 to –0.59 A F−1 and a decrease in Na+,K+‐ATPase current from 1.09 A F−1 to 0.54 A F−1 during CH. These changes persisted as HF developed (INa,late increased to –0.82 A F−1 and Na+,K+‐ATPase current decreased to 0.51 A F−1). Sarcoplasmic reticulum (SR) Ca2+ content increased during CH then decreased in HF (from 32 to 15 μm l−1) potentially supporting the maintenance of FS in the whole heart and Ca2+ transients in single myocytes during the former stage. We showed using glycoside blockade in healthy myocytes that increases in SR Ca2+ content and Ca2+ transients can be driven by the same amount of inhibition of the Na+,K+‐ATPase as measured in the diseased cells. SERCA function remains constant in CH but decreases (τ for SERCA‐mediated Ca2+ removal changed from 6.3 to 3.0 s−1) in HF. In HF there was an increase in spark frequency and spark‐mediated Ca2+ leak. We suggest an increase in INa,late and a decrease in Na+,K+‐ATPase current and function alters the balance of Ca2+ flux mediated by the Na+/Ca2+ exchange that limits early contractile impairment.

The influence of moderate and low insulin antibody levels on insulin absorption and plasma free insulin profiles is uncertain. Two groups of six C-peptide negative diabetic patients, one with low (3.8 +/- 0.8 mu/l) and one with moderate (16.4 +/- 2.0 micrograms/l) serum insulin antibody levels, were studied. Subjects were given 0.3 U/kg neutral human or acid bovine soluble insulin subcutaneously in random order before breakfast on separate days. Moderate antibody levels significantly blunted the rise in plasma free insulin that followed injection of the human and bovine insulins (p less than 0.05). The rise in blood glucose after breakfast was significantly greater in patients with moderate antibody levels (p less than 0.05) and more marked following the bovine than the human insulin (p less than 0.05). Plasma free insulin, blood glucose and 3-hydroxybutyrate profiles suggest that acid bovine soluble insulin has a significantly more protracted action than neutral human insulin.

Six C-peptide deficient diabetics receiving twice daily mixtures of short and intermediate acting insulins were selected for study because of persistently raised blood glucose concentrations before and after breakfast. They were investigated to assess the effect of moving their evening injection of intermediate acting insulin to bedtime. The patients' usual twice daily insulin treatment was optimised and compared with the bedtime regimen during inpatient metabolic studies and an outpatient crossover study. With the conventional injection regimen blood glucose concentration rose sharply from 0500 to reach a fasting mean value of 10± SE 16 mmol/l (180 + 29 mg/100 ml) and 16 8 l 222 mmol/l (303 ± 40 mg/100 ml) after breakfast. By contrast, when the evening dose of intermediate acting insulin was delayed until bedtime the nocturnal rise in blood glucose concentration started later and was significantly lower both fasting (75 ± 1 1 mmol/l (135±20 mg/100 ml); p<002) and after breakfast (13 2 ± 1 4 mmol/l (238 ± 25 mg/100 ml); p < 0 02). Fasting blood concentrations of ketone bodies (3-hydroxybutyrate) were also significantly decreased. Plasma free insulin concentrations showed the predicted changes in five of the six patients. Blood glucose profiles collected over four months during the outpatient study confirmed the beneficial effect of giving intermediate acting insulin at bedtime.

We report a flexible light-sheet fluorescence microscope (LSFM) designed for studying dynamic events in cardiac tissue at high speed in 3D and the correlation of these events to cell microstructure. The system employs two illumination-detection modes: the first uses angle-dithering of a Gaussian light sheet combined with remote refocusing of the detection plane for video-rate volumetric imaging; the second combines digitally-scanned light-sheet illumination with an axially-swept light-sheet waist and stage-scanned acquisition for improved axial resolution compared to the first mode. We present a characterisation of the spatial resolution of the system in both modes. The first illuminationdetection mode achieves dual spectral-channel imaging at 25 volumes per second with 1024 × 200 × 50 voxel volumes and is demonstrated by time-lapse imaging of calcium dynamics in a live cardiomyocyte. The second illumination-detection mode is demonstrated through the acquisition of a higher spatial resolution structural map of the t-tubule network in a fixed cardiomyocyte cell. K E Y W O R D S cardiac, fluorescence, high-speed, light-sheet, microscopy