Agonist-sensitive calcium stores in arteries from steroid hypertensive rats.

The present study characterizes cellular calcium stores that are sensitive to norepinephrine and caffeine in arteries from deoxycorticosterone acetate hypertensive rats. Mesenteric arteries from normotensive and hypertensive rats were excised and cut into helical strips for isometric force recording. In calcium-free solution, phasic contractile responses to norepinephrine (5.9 x 10(-9) to 5.9 x 10(-6) M), but not caffeine (0.3-30 mM), were greater in hypertensive arteries. D-600, a calcium channel blocker, or removal of the endothelium did not alter phasic contractions to norepinephrine or caffeine. In contrast, contractions to both norepinephrine and caffeine were inhibited by ryanodine, a drug that depletes calcium from intracellular stores. An inhibitor of phospholipase C (2-nitro-4-carboxyphenyl N,N-diphenylcarbamate) attenuated contractions to norepinephrine but not those to caffeine. The augmented response to norepinephrine in hypertensive rats did not occur early after implantation of the mineralocorticoid, suggesting that this vascular change may not play a role in the development of high blood pressure in this experimental model. The augmented response to norepinephrine was reduced in mineralocorticoid-treated rats maintained on a low sodium diet, and these rats had blood pressures in the normotensive range. Because contractile responses to caffeine were not enhanced in arteries from hypertensive rats, we conclude that the cellular store for calcium is not enlarged compared with that in normotensive arteries. In contrast, the mobilization of calcium from cellular stores by norepinephrine is augmented in mineralocorticoid hypertension. This augmented response may be linked to altered phospholipase C activity and thus to an augmented action of inositol trisphosphate that releases calcium from intracellular sites.

Dehydration: biological considerations, age-related changes, and risk factors in older adults.

Maintenance of water balance is essential to normal physiologic function and vigorous aging. Older adults, however, frequently experience alterations in fluid homeostasis, which result in dehydration. This article describes the physiology of water balance, age-related changes that influence fluid regulation, and associated risk factors for dehydration in older adults. Fluid hygiene is an important health promotion activity for this age group, but when efforts to prevent imbalance are unsuccessful, early identification and intervention to correct problems should be done to minimize adverse consequences. Although much is known about fluid homeostasis, dehydration, and contributory factors in the aging process, water disorders remain prevalent in this group. A great deal of work is still needed to determine "best practices" and creative clinical interventions to support adequate fluid intake behaviors. Both quality management programs and research studies provide avenues for systematic evaluation.

SANS study of the distribution of water within starch granules.

This study describes contrast variation small angle neutron scattering (SANS) experiments which focus on the role which the intra-granular room temperature distribution of water and carbohydrate plays in determining the native structure and subsequent functionality of starch. It is shown that variations in botanical origin and amylose content do not correlate with significant differences in room temperature composition of A-type starch granules. In turn, variations in the gelatinisation behaviour of A-type starches do not correlate with variations in room temperature water distribution. In contrast, the room temperature water content is found to differ significantly between granules of potato (B-type) and a range of A-type starch cultivars. A correlation is found between these compositional differences and variations in crystal structure, which has implications for biological growth conditions and gelatinisation behaviour.

Relaxation technique and postoperative pain in patients undergoing cardiac surgery.

A two-group pretest and posttest quasi-experimental design was used to determine the effectiveness of a slow, deep-breathing relaxation technique in relieving postoperative pain after coronary artery bypass graft surgery. A convenience sample of 29 subjects was divided into an experimental group (n = 15), who received relaxation training on the evening before surgery and performed the technique after surgery, and a control group (n = 14), who did not receive relaxation training. Analysis of variance was used to analyze the data. Significant decreases were demonstrated as a result of relaxation, in blood pressure, heart rate, respiratory rate, and report of pain on the visual descriptor scale. No significant differences were seen in analgesic use or visual analogue scale scores. Eleven subjects (73.3%) said the technique was helpful in their pain management. All experimental subjects stated that the relaxation technique was simple to perform, and they would recommend it to others who have postoperative pain.

Feminist empiricism as a method for inquiry in nursing.

Feminist empiricism may provide a valuable approach for the acquisition, evaluation, and integration of biological knowledge in nursing epistemologies. This article discusses feminist empiricism as a method for inquiry in nursing. Proponents of feminist empiricism strive to work within the current political, social, and scientific structures while acknowledging that all three of these structures must change if less distorted epistemologies are to emerge. Hypertension in women is used to illustrate how feminist empiricism could be used to modify the traditional scientific approach. The argument is made that the androcentricism of the traditional scientific approach must be changed in order to include the problematics of women. Moreover, women must have a central role in determining the problematics of both health and illness in women. A philosophical stance embracing holism cannot deny biological phenomena or preclude research on these phenomena. Theorists and scientists in nursing have a unique opportunity to reconceptualize biological phenomena, from a holistic perspective, in the development of epistemologies for nursing. An argument for the use of basic research as a quantitative methodology, from a feminist perspective, is made. The appropriateness, for nursing, of basic research methodologies to generate knowledge about biological processes, which are within nursing's scientific domain, are discussed.

Effect of supplemental dietary calcium on the development of DOCA-salt hypertension in weanling rats.

This study characterizes the response to dietary calcium in DOCA-salt hypertension. Body weight, systolic blood pressure, and total serum calcium levels were compared among normotensive control rats, DOCA-salt hypertensive rats treated with calcium carbonate (CaCO3) augmentation, and DOCA-salt hypertensive rats without supplementary dietary calcium. Dietary calcium augmentation prevented the rise of blood pressure that is normally produced by DOCA-salt. Attenuation in systolic blood pressure was independent of weight loss or total serum calcium and may be linked to alterations in calcium homeostasis that are seen in both human and experimental hypertension. Thus this study provides important data that may assist in further explicating the role that alterations in calcium homeostasis play in DOCA-salt hypertension. Further, these data may also be important in the identification of a nonpharmacological intervention for testing in humans.