Ovum transport in mammalian oviducts involves two main effectors: ciliary motility and muscle contractility. To study the relative contribution of cilia to ovum transport in the rat, we blocked smooth muscle activity with isoproterenol, a beta-adrenergic agonist, and measured transport rates of surrogate ova in situ. Transport rates before isoproterenol administration were 0.04 mm/s in the cephalic ampulla and 0.03 mm/s in the caudal ampulla; rates were unchanged after administration of isoproterenol. To determine if isoproterenol affected ciliary activity, we measured ciliary beat frequency with laser-scattering spectroscopy over the effective isoproterenol dosage. Isoproterenol did not cause a significant change in ciliary beat frequency. Our results show that in the rat oviductal ampulla, ciliary motion is capable of transporting ova in the absence of muscle contractility.

The purpose of the present study was to determine the changes in intracellular ionized calcium concentration ([Ca2+]i) or [Ca2+]i sensitivity accompanying spontaneous and agonist-induced contraction of human myometrium at term pregnancy, as well as to quantify the response to three prototypical agonists: 1) oxytocin, 2) vasopressin, and 3) phenylephrine. Uterine biopsies were obtained at the time of cesarean section from patients who delivered at or near full-term gestation. These preparations were used to measure isometric force development and [Ca2+]i levels with the luminescent calcium indicator aequorin. Concentration-response relationships were determined with respect to isometric force development in the presence of the agonist. [Ca2+]i-force relationships were determined with respect to spontaneous phasic contractions, as well as agonist-induced phasic and tonic contractions. The results provide evidence that the phasic nature of term human myometrium is due to 1) the resting [Ca2+]i level being less than the calcium threshold for contractions and 2) the inability of the tissue to maintain high [Ca2+]i levels for prolonged periods of time. In addition, calcium-independent mechanisms of regulation were suggested by the relatively minor calcium sensitizing action of oxytocin and the observation that relaxation of tonic contractions preceded the fall in [Ca2+]i levels.

Rowing is a unique exercise for humans, and the imposed biomechanical motion may alter both respiratory mechanics and timing. To investigate the ventilatory patterns of competitive rowers while rowing, we studied the pulmonary function of eight members of the University of Washington Women's Crew and one former member of the 1984 Women's Olympic Rowing Team on a rowing ergometer. Ventilatory performance of the oarswomen was compared both with their performance to exhaustion on a cycle ergometer and with the ventilatory response of six untrained controls on a rowing and a cycle ergometer. We found rowing elicited a higher ventilatory response in both the oarswomen and controls in submaximal and maximal work loads (P less than 0.001). Both oarswomen and controls had higher maximal breathing frequencies when rowing compared with cycling [rowers, 54.7 +/- 1.9 vs 49.8 +/- 0.09 (SE) breaths/min, P less than 0.05; and controls, 53.6 +/- 2.5 vs. 49.2 +/- 4.7, P less than 0.05] and lower maximal tidal volumes (rowers, 1.94 +/- 0.12 vs. 2.21 +/- 0.09 liters, P less than 0.01; controls, 1.59 +/- 0.09 vs. 1.68 +/- 0.19, difference not significant). Both oarswomen and controls were more hypocapnic while rowing compared with cycling (rowers, P less than 0.001; controls, P less than 0.02), although oarswomen were less hypocapnic while rowing than nonrowers (P less than 0.03). These results indicate that rowing causes hyperventilation with a higher breathing frequency and lower tidal volume. This alteration of pattern is possibly secondary to a change in mechanics, which possibly arises from the generation of high exercise ventilation in a variable seated position.

The unexplained behavior of egg retention at the ampulloisthmic junction (AIJ) is a mechanical phenomenon; therefore the key to this process must lie in the anatomy of the oviduct. To investigate the concept that simple anatomical differences between ampulla and isthmus cause AIJ retention, we quantified, in these two regions of the rabbit oviduct, the structural characteristics of the tubal wall that show marked differences: wall thickness and luminal caliber. The oviductal wall greatly increases in thickness and decreases in luminal caliber abruptly at the transition from ampulla to isthmus. These passive mechanical factors predict a dramatically reduced distensibility of the isthmic wall compared to that of the ampulla, and these factors provide us with a simple model to account for the apparent sphincteric activity of the AIJ. Actual measurements of tubal distensibility confirmed our prediction. In addition, egg transport studies following microsurgical removal of the AIJ showed normal transport, an indication that no special structure need exist at the AIJ. We conclude that the contrasting morphology of the ampulla and isthmus may suffice to explain AIJ retention, and no special active mechanism need be postulated.