Osmotic Pressure Levels Research Articles

Germination of Six Alfalfa Varieties at Three Levels of Osmotic Pressure1

Germination of Six Alfalfa Varieties at Three Levels of Osmotic Pressure¹

Seasonal changes in human body fluids.

Seasonal alterations of distribution and amount of water and salts were studied on adult male subjects at basal condition and following results were obtained.1) The serum water content increases in summer and decreases in winter, while the serum protein concentration and the hematocrit present reverse changes.2) The total circulating serum volume as well as the blood volume also undergo the same course of seasonal changes. The serum volume is higher in summer than in winter by 8.6% of the annual mean, and the change of blood volume is mainly effected by that of serum volume.3) As the total circulating serum protein is maintained almost constant throughout the year, the above mentioned seasonal changes are mainly due to hemodilution in summer and hemoconcentration in winter by changes of water content in circulating serum.4) The total body water (TBW), the extracellular fluid (ECF) and the intracellular fluid (ICF), all increase in summer and decrease in winter. The percentage change of ECF is the most remarkable among the others, while theabsolute amount of ICF change approximately coincides with that of ECF change, because ICF is far higher in its absolute volume than ECF. The seasonal change of water amount in circulating serum seems to be mainly effected by the change of ECF.5) The water metabolism, including the intake of water and its elimination from the body, increases in summer and decreases in winter and thus the water balance is maintained at zero level in each season after the acclimatization has been attained. Seasonal change of total water output is mainly due to that of the total perspiration (insensible water loss sweating), which undergoes a similar change, while the urinary output changes reversely.6) The ADS content in serum increases in summer and decreases in winter, while the level of osmotic pressure in serum presents a reverse change. From these, it is presumed that the central regulatory mechansim of water metabolism, including the functions of the osmoregulatory centre and pituitary gland, is put in function to conform to seasonal change of water elimination, especially of perspiration.7) Seasonal variations of serum water, ECF, ICF and TBW can be explained by this postulation of climatic adaptation of water metabolism. The seasonal variation of urinary excretion can also be explained by this change of central control of water metabolism, i.e. change of water reabsorption from kidney due to seasonal change of ADH secretion.8) Na, Cl and K concentrations in serum show also seasonal variations, decreasing in summer and increasing in winter. The change of K concentration is far larger than the other two, and thus the ratio of Na/K increases in summer while it decreases in winter.9) The total Na and Cl contents in circulating serum and as well as in ECF increase in summer and decrease in winter, while the total K content in both compartments changes reversely. From these, it is suggested that secretion of mineral corticoid may undergo a seasonal variation.

Diluters for Bovine Semen. VIII. The Effects of Alterations of Some Physical Factors of a Milk Diluter on the Livability of Bull Spermatozoa1,2

Summary The effects of alterations in the pH, osmotic pressure, and electrolyte concentration of a cysteine-treated nonfat dry milk solids diluter on the livability of bull spermatozoa have been investigated. There were no differences in livability between the two osmotic pressure levels studied (approximately −0.50° C. and −0.70° C.) and no appreciable differences among the pH levels studied (6.2, 6.6, and 7.0). The addition of either 5.0 or 10.0ml. of 0.5 N NaCl solution to 100ml. of diluter resulted in significantly improved livability. A highly significant interaction between pH and electrolyte concentration indicated that higher pH levels require higher levels of electrolytes. Neither the pH nor the osmotic pressure of the diluter changed appreciably during a 12-day storage period. It was concluded that no improvement in spermatozoan livability can be expected by alteration of the pH, osmotic pressure, or buffering capacity of the diluter employed but that the addition of 0.5 N NaCl results in slightly improved livability.