Decline In Cell Volume Research Articles

ABA Accumulation in Dehydrating Leaves Is Associated with Decline in Cell Volume, Not Turgor Pressure.

Reanalysis of published experimental data shows that in dehydrating leaves ABA accumulation is linked with reduction of cell volume rather than turgor, providing clues toward signaling mechanisms.

Further studies on the effects of intracrine and extracellular angiotensin II on the regulation of heart cell volume. On the influence of aldosterone and spironolactone

The influence of extracellular and intracellular angiotensin II (Ang II) on the cell volume in the failing heart of cardiomyopathic hamsters (TO2) was further investigated as well as the influence of aldosterone and spironolactone on the Ang II action on cell volume. Measurements of cell width and area of quiescent ventricular cardiomyocytes were performed using a video camera and computer analysis and the relative cell volume was calculated. All measurements of cell volume were performed in the same cell before and after the administration of Ang II (10 − 8 M). The results indicated that: a) the increase in cell volume caused by extracellular Ang II(10 − 8 M) was enhanced in cells incubated with aldosterone (100 nM) for 48 h; b) the effect of aldosterone was abolished by spironolactone (10 − 8 M); c) the decline in cell volume elicited by intracellular administration of Ang II (10 − 8 M) was increased by aldosterone and inhibited by spironolactone; d) the effects of aldosterone and spironolactone were related, in part, to a change in expression of AT1 receptors; and e) the intracellular administration of Ang II reduced the swelling-dependent chloride current (I Clswell). The implications of these findings to the failing heart and myocardial ischemia are discussed.

Cell swelling, impulse conduction, and cardiac arrhythmias in the failing heart. Opposite effects of angiotensin II and angiotensin (1–7) on cell volume regulation

The influence of hypotonic solution on cell volume and electrophysiology properties of the failing heart of cardiomyopathic hamsters (TO-2) was investigated. The results showed an increase in cell volume of quiescent isolated ventricular myocytes by 66% within 30 min. Angiotensin (1-7) [Ang (1-7)] (10(-8) M) administered to isotonic solution, elicited a gradual decline in cell volume and a significant decrease of the swelling-activated chloride current (I (Clswell)). The effect of Ang (1-7) on cell volume was inhibited by ouabain (10(-7) M). Angiotensin II (10(-8) M) caused cell swelling and increased I (Clswell). Experiments performed on isolated left ventricles of cardiomyopathic hamsters at an advanced stage of the disease, indicated that hypotonic solution prepared by diluting the normal Krebs solution by 25%, showed a gradual decrease of conduction velocity, generation of early after depolarizations and block of impulse conduction within 10 min. Implications to myocardial ischemia are discussed.

Proliferation-associated oxygen consumption and morphology of tumor cells in monolayer and spheroid culture.

The oxygen consumption rate, proliferative activity, and morphology of EMT6/Ro mouse mammary sarcoma cells in monolayer and multicellular spheroid culture have been investigated in a comparative study. During the transition of monolayer cells from the exponential into the plateau growth phase, there is a distinct decrease in the cellular volume that is associated with a corresponding decrease in the proliferative and respiratory activity of the cells. The decline in cell volume is mainly due to a decrease in the content of cytoplasm, whereas the size of the nucleus is only slightly reduced. A concomitant decrease in the number of mitochondria per cell obviously accounts for the reduction in cellular oxygen uptake. Despite a continuous decrease of cell proliferation from the surface to interior regions of EMT6 spheroids reflected by a gradient in tritiated thymidine labeling, volume-related oxygen consumption is rather uniform in viable regions of these aggregates. The finding can be explained by the results of the morphometric evaluation showing a uniform volume density of mitochondria, i.e., of oxygen-consuming sites within these spheroids.

Observations on the in vivo aging of red cells in the rat.

Aging of rat erythrocytes was studied in vivo by two experimental models. In the first, a single cohort of erythrocytes labelled with radioiron was followed; in the second, sequential hypertransfusions were employed to obtain a defined red cell population, which was continuously transferred from host to host. The results are compatible with a normal red cell life span of about 60 days and with sequestration of senescent erythrocytes in the spleen and in the liver. Red cell aging was associated with a decline in cell volume, haemoglobin, G6PD and ATP content. There were no measureable changes in osmotic fragility. Thus, changes in osmotic resistance do not appear to be critical factors limiting the life span of circulating erythrocytes in the rat.

The cytotoxic principle of the phytoflagellate Prymnesium parvum.

The cytotoxic events leading to lysis induced in Ehrlich ascites tumor (E.A.) cells by Prymnesium parvum cell extracts were followed microscopically and measured quantitatively as changes in E.A. cell volume, uptake of trypan blue, and release of macromolecular constituents from the cells. Cell swelling was the most immediate response to P. parvum cytotoxin, while cell death and lysis were later events distinguished by a decline in cell volume, uptake of dye, and appearance of cellular macromolecules free in the incubation medium. The pH and temperature were shown to affect the outcome of the lytic sequence. At either low pH or temperature, cells swelled but did not lyse until the pH or temperature was raised. On the other hand, cells swollen at the higher pH or temperature could be protected from lysis by lowering either the pH or the temperature.