Victor Fajardo

Temporal coordination of pelvic and perineal striated muscle activity during micturition in female rabbits.

PURPOSE To determine the motor basis of urine expulsion the activity of the pelvic (pubococcygeus) and perineal (bulbospongiosus and ischiocavernosus) muscles was recorded during micturition in anesthetized female rabbits. MATERIAL AND METHODS Virgin female chinchilla rabbits were used for simultaneously recording cystometrograms and electromyograms of the pubococcygeus, ischiocavernosus and bulbospongiosus muscles. The particular contribution of each muscle during micturition was analyzed in another set of experiments in which each was inactivated by bilateral lidocaine injection. Bladder function was assessed using standard urodynamic parameters. RESULTS Cystometrography showed that micturition comprises 2 phases, that is storage and voiding phases. During the latter phase no high frequency oscillations were recorded. On simultaneous electromyography recordings a temporal, coordinated activation of pelvic (pubococcygeus) and perineal (bulbospongiosus and ischiocavernosus) muscles was observed. During specific blockade of each muscle some modifications in urodynamic parameters were found. CONCLUSIONS Our findings indicate a specific role for the pelvic and perineal muscles during feminine micturition.

Differences in morphology and contractility of the bulbospongiosus and pubococcygeus muscles in nulliparous and multiparous rabbits

In women, birth trauma can result in altered anatomy of supporting structures of the pelvic floor and in the development of urinary incontinence. The goal of this study was to investigate the association between parturition and the morphology and function of perineal and pelvic muscles in the female rabbit. In ten nulliparous and ten multiparous same-age females, we investigated morphological, histological (n = 5 females/group), and contractile characteristics (n = 5 females/group) of the perineal bulbospongiosus (Bsm) and the pelvic pubococcygeus (Pcm) muscles. Bsm and Pcm muscles of multiparous females were significantly lighter, they had a smaller cross-sectional fiber area, and developed significantly lower twitch and tetanic tension force in response to electrical stimulation than muscles of nulliparous females. In female rabbits, multiparity is associated with potentially pathological changes in the morphological and functional characteristics of these perineal and pelvic muscles, possibly as a result of stretching during parturition.

Multiparity causes uncoordinated activity of pelvic- and perineal-striated muscles and urodynamic changes in rabbits.

Temporal and coordinated activation of pelvic- (pubococcygeous) and perineal- (bulbospongiosus and ischiocavernosus) striated muscles occurs during micturition in female rabbits. We have hypothesized that the coordinated activation of pelvic and perineal muscles is modified during the micturition of young multiparous rabbits. Young virgin and multiparous female chinchilla rabbits were used to simultaneously record cystometrograms and electromyograms of the pubococcygeous, ischocavernosus, and bulbospongiosus muscles. Bladder function was assessed using standard urodynamic variables. The temporal coordination of pelvic- and perineal-striated muscle activity was changed in multiparous rabbits. The cystometrogram recordings were different than those obtained from virgin rabbits, as seen in alterations of the threshold volume, the residual volume, the voiding duration, and the maximum pressure. In rabbits, we find that multiparity causes uncoordinated activity of pubococcygeous, ischiocavernosus, and bulbospongiosus muscles and modifies the urodynamics.

Is food quality important for carnivores? The case of Puma concolor

The composition and energetic content of puma (Puma concolor) diet in Sierra Nanchititla Natural Reserve (SNNR), Mexico, were determined. We collected 183 scats, where 27 components were identified by occurrence (88.07% mammals). The pumas diet was mainly composed of armadillo (Dasypus novemcinctus, 40.33%), white-nosed coati (Nasua narica, 11.93%) and white-tailed deer (Odocoileus virginianus, 6.17%). Energetic analysis of prey indicates that the puma prefers those with higher energetic content (kcal/kg). The prey with the most energetic contribution is armadillo (2398.70 kcal/kg), followed by white-nosed coati (2225.25 kcal/kg) and finally white-tailed deer (2165.52 kcal/kg). The differences in energetic content between prey species were statistically significant. The number of individuals killed/year on average to support a puma was 51 armadillos, 16 white-tailed deer and 7 white-nosed coatis. The results indicate a greater consumption of prey that provide more kilocalories to the predator, and suggests the importance of quality meat in the diet of pumas.

A Mountain or a Plateau? Hematological Traits Vary Nonlinearly with Altitude in a Highland Lizard.

High-altitude organisms exhibit hematological adaptations to augment blood transport of oxygen. One common mechanism is through increased values of blood traits such as erythrocyte count, hematocrit, and hemoglobin concentration. However, a positive relationship between altitude and blood traits is not observed in all high-altitude systems. To understand how organisms adapt to high altitudes, it is important to document physiological patterns related to hypoxia gradients from a greater variety of species. Here, we present an extensive hematological description for three populations of Sceloporus grammicus living at 2,500, 3,400, and 4,300 m. We did not find a linear increase with altitude for any of the blood traits we measured. Instead, we found nonlinear relationships between altitude and the blood traits erythrocyte number, erythrocyte size, hematocrit, and hemoglobin concentration. Erythrocyte number and hematocrit leveled off as altitude increased, whereas hemoglobin concentration and erythrocyte size were highest at intermediate altitude. Additionally, lizards from our three study populations are similar in blood pH, serum electrolytes, glucose, and lactate. Given that the highest-altitude population did not show the highest levels of the variables we measured, we suggest these lizards may be using different adaptations to cope with hypoxia than lizards at low or intermediate altitudes. We discuss future directions that research could take to investigate such potential adaptations.

Visceral Branches of the Abdominal Aorta in the New Zealand Rabbit: Ten Different Patterns

La aorta abdominal del conejo ha sido objeto de estudio e investigacion para desarrollar nuevas plataformas de entrenamiento para protocolos diagnosticos y terapeuticos asi como para probar las virtudes de materiales y equipos endovasculares, sin embargo, existen muy pocas descripciones en la literatura de las ramas viscerales que emergen de la aorta abdominal en esta especie. Las variaciones anatomicas son eventos de ocurrencia comun y por lo tanto deben ser considerados para realizar investigacion y ensayos clinicos. El objetivo del presente estudio ha sido describir los diferentes patrones que pueden presentar las ramas viscerales que emergen de la aorta abdominal en el conejo.