Mature beef cows were slaughtered at 5 (n = 6), 10 (n = 6), 20 (n = 6) or 30 (n = 5) d after calving to identify endocrine events that may affect the duration of postpartum anestrus. Additional cows (n = 6) were slaughtered 12 to 14 d after their first postpartum estrus (luteal phase cows). Anterior pituitary concentrations of luteinizing hormone (LH) were low at d 5 (383 +/- 69 micrograms/g), ...

Isolated segments of the guinea pig circumflex coronary artery were stimulated transmurally with brief duration (0.05 msec) pulses while recording intracellularly. Resting membrane potential was -60.3 +/- 4.3 mV (n = 66). Transient depolarizations (TDs) graded in amplitude with stimulus intensity were elicited with single stimuli. An action potential of 47 +/- 5 mV was superimposed upon the TD ...

Calcium binding to isolated adipocyte microsomes enriched in endoplasmic reticulum has been characterized. Binding was concentration-dependent, saturable, and totally dissociable. Steady state was reached within 20 min at all calcium concentrations tested. Three apparent classes of binding sites were identified in kinetic and steady state studies using calcium concentrations from 1 muM to 10 mM...

To study the effects of magnesium (Mg2+) on human coronary arteries and to compare those effects with those of diltiazem and nitroglycerin, we measured the tension of ring segments from isolated human coronary arteries obtained at autopsy within 5 hours after death. Precontracted segments with 3 x 10(-6) M prostaglandin F2 alpha were studied after adding cumulative concentrations of these agent...

Upon impalement with a microelectrode in a Ca-free medium containing 5 mM ATP, a Chlamydomonas cell lost its flagellar activity within 45 s, and the injection of either positive or negative direct current did not stimulate the flagella to beat after that time. When 3 mM Mg l + was added to the external medium, the impaled cell exhibited a flagellar frequency of 22 ± 7 Hz. With 5 mM ATP and 3 mi...

A spectrophotometric method for the determination of total carbonate in water samples was developed. The method is based on the color change of an acid-base indicator in relation to the concentration of permeable gas substances through a membrane. By using a new portable FIA system equipped with a gas-diffusion unit, a highly sensitive and on-site determination of total carbonate in aqueous sol...

A phosphatase specific for the hydrolysis of 3-deoxy-d-manno-octulosonate (KDO)-8-phosphate was purified approximately 400-fold from crude extracts of Escherichia coli B. The hydrolysis of KDO-8-phosphate to KDO and inorganic phosphate in crude extracts of E. coli B, grown in phosphate-containing minimal medium, could be accounted for by the enzymatic activity of this specific phosphatase. No o...

To test whether the pressure-volume relationship of the canine small intestinal vasculature is linear over the normal range of portal venous pressures (5 to 35 mm Hg), we used two methods to measure volume: (1) the integral of inflow minus outflow (IFD), and (2) tissue activity of 51Cr-labeled erythrocytes (Cr-51). Venous pressures were changed in steps of 5 mm Hg with a servo-controlled system...

A neuroblastoma X glioma hybrid cell line with well-developed neural properties was found that has high-affinity morphine receptors. The average cell contains approximately 3 X 105 receptors. In contrast, parent cells and other neuroblastoma or hybrid cell lines tested had few or no morphine receptors. Membrane preparations that bind narcotic analgesics such as morphine and its congeners have b...