Age and hypertrophy alter the contribution of sarcoplasmic reticulum and Na+/Ca2+ exchange to Ca2+ removal in rat left ventricular myocytes.

Age and hypertension contribute significantly to cardiac morbidity and mortality, however the importance of each during the progression of hypertrophy is unclear. This investigation examined the effect of age and hypertension on Ca(2+) handling in rat ventricular myocytes by comparing a genetic model of hypertension and cardiac hypertrophy (spontaneously hypertensive rat, SHR) with its normotensive control (Wistar-Kyoto rat, WKY) at 5 and 8 months of age. Experiments were performed on single left ventricular myocytes isolated from SHR or WKY hearts.

Antagonistic actions of halothane and sevoflurane on spontaneous Ca2+ release in rat ventricular myocytes.

Background: Halothane has been reported to sensitize Ca(2+) release from the sarcoplasmic reticulum (SR), which is thought to contribute to its initial positive inotropic effect. However, little is known about whether isoflurane or sevoflurane affect the SR Ca(2+) release process, which may contribute to the inotropic profile of these anesthetics.

Methods: Mild Ca(2+) overload was induced in isolated rat ventricular myocytes by increase of extracellular Ca(2+) to 2 mM.

Decreased Ca2+ extrusion via Na+/Ca2+ exchange in epicardial left ventricular myocytes during compensated hypertrophy.

Hypertension-induced cardiac hypertrophy alters the amplitude and time course of the systolic Ca2+ transient of subepicardial and subendocardial ventricular myocytes. The present study was designed to elucidate the mechanisms underlying these changes. Myocytes were isolated from the left ventricular subepicardium and subendocardium of 20-wk-old spontaneously hypertensive rats (SHR) and age-matched normotensive Wistar-Kyoto rats (WKY; control).

The effects of alfentanil on cytosolic Ca(2+) and contraction in rat ventricular myocytes.

Unlabelled: Previous investigations of the effects of potent opioid analgesics on the heart have concentrated on effects on contraction magnitude and time course, but little is known about their effects on cytosolic Ca(2+) regulation in cardiac tissue. In this study, we sought to assess the effects of alfentanil on contractility and the cytosolic Ca(2+) transient in ventricular myocytes isolated from the rat ventricle by enzymatic dispersion. Cells were loaded with fura-2 and electrically stimulated at 1 Hz, and Ca(2+) transients and contractions were recorded optically at 30 degrees C.

Resilience of epilithic algal assemblages in atmospherically and experimentally acidified boreal lakes.

Algal assemblages can be highly responsive to environmental changes in recovering acidified lakes. We compared epilithic algal assemblages in boreal lakes during chemical recovery from atmospheric (Killarney Park, Ontario) and experimental (Lake 302S, Experimental Lakes Area, Ontario) acidification to assess the impact of spatial and temporal scale of severe acidification on taxonomic resilience (i.e.