The haeniatological and rheological characteristics of blood from seven marine mammal species have been examined to determine the relationship between increased haematocrit. which is correlated with ability increase aerobic dive limits. viscosity. reflect adaptations a variety niches ranging coastal pelagic iceedge environments. exhibit wide range diving behaviours. Average haematocrits ranged from43–45% in bottlenose dolphins. killer whales California sea lions more than 60% deeper (beluga...

Physiological vagility represents the capacity to move sustainably and is central fully explaining processes involved in creating fine-scale genetic structure of amphibian populations, because movement (vagility) duration determine dispersal distance individuals can interbreed. The tendency for amphibians maintain differentiation over relatively short distances (isolation by distance) has been attributed their limited (low vagility) compared with other vertebrates. Earlier studies analyzing...

SUMMARY Isolated brainstem preparations from larval (tadpole) and adult Rana catesbeiana were used to examine inhibitory mechanisms for developmental regulation of the respiratory central pattern generator (CPG). Preparations superfused at 20-22 °C with Cl--free artificial cerebrospinal fluid (aCSF) or aCSF containing agonists/antagonists ofγ-aminobutyric acid (GABA) glycine receptors. Respiratory motor output CPG, measured as neural activity cranial nerve roots, was associated fictive gill...

ABSTRACT The role of central chemosensitivity in the control ventilation fishes was investigated directly by perfusing a mock extradural fluid (EDF) through cranial space medullary region conscious air-breathing fish, Amia calva. Perfusions with Sudan Black dye showed that EDF communicated cerebrospinal (CSF) and entered cerebral ventricles. Altering , and/or pH had no effect on gill- or rates, heart rate blood pressure during exposure to normoxic water. Aquatic hypoxia, however, stimulated...

Elephant seals offer a unique opportunity to examine rheological characteristics of blood because the normally high hematocrits in this species. A comparison viscosity elephant seal with that terrestrial mammal (rabbit; HCT = 35%) reveals threefold increase over rabbit due hematocrit (HCT 65%). While increased reflects oxygen storage capacity, transport may actually be reduced by effects on flow. plasma was also higher than plasma; associated concentration proteins. There were no apparent...

The aim of this study was to examine the effects cellular hypoxia, and contribution anaerobic metabolism, on respiratory activity in bullfrogs at different stages development. Respiratory-related neural recorded from cranial nerve rootlets isolated brainstem preparations pre-metamorphic (Taylor-Kollros (T-K) VIII-XVI) postmetamorphic tadpoles (T-K XXIV-XXV) adults. Changes fictive gill/lung brainstems lung adults were examined during superfusion with control (98% O(2)/2% CO(2)) or hypoxic...

This study examined the direct effects of tricaine methanesulfonate (MS-222), a sodium-channel blocking local anesthetic, on respiratory motor output using an in vitro brain stem preparation adult North American bullfrogs ( Rana catesbeiana). Bullfrogs were anesthetized with halothane, and was removed superfused artificial cerebrospinal fluid containing MS-222 at concentrations ranging from 0.1 to 1,000 μM. At lowest concentration MS-222, frequency f R ) increased significantly P < 0.05),...

August Krogh (1874–1949) was amongst the most influential physiologists in first part of 20th century. This an era when physiology emerged as a quantitative research field and many current physiological disciplines were defined; can rightfully be viewed having introduced comparative physiology, epithelial transport – together with Johannes Lindhard exercise independent disciplines. With unique ability to design construct equipment, could address novel questions both human animal...

SUMMARY Anurans (frogs and toads) generate lymphatic fluid at 10 times the rate in mammals, largely as a consequence of their very `leaky' vasculature high interstitial compliance. Lymph is ultimately pumped into venous system by paired, dorsally located lymph hearts. At present, it unclear how that accumulates central body subcutaneous sacs moved to anterior posterior hearts axillary regions moved, against gravity, In this study,we tested hypothesis lung ventilation, through its consequent...

Electromyographic (EMG) activity of skeletal muscles that either insert on the skin or are associated with margins subcutaneous lymph sacs was monitored for two species anurans, Chaunus marinus and Lithobates catesbeiana (formerly Bufo Rana catesbeiana). Our hypothesis contraction these varies volume, hence pressure, within sacs, this pressure is responsible moving from ventral, gravitationally dependent reaches body to dorsally located hearts. EMG M. piriformis, gracilis minor, abdominal...

Amphibians have a single ventricle and common conus arteriosus that produces an equal pressure to the parallel pulmocutaneous systemic vascular circuits. The distribution of blood flows between () circuits (net cardiac shunt) varies with number environmental conditions behaviours; although autonomic regulation pulmonary resistance conductance has been emphasized, little attention paid possible contribution passive physical characteristics two changes associated variation in output. In this...

To accommodate the pronounced metabolic response to digestion, pythons increase heart rate and elevate stroke volume, where latter has been ascribed a massive fast cardiac hypertrophy. However, numerous recent studies show that mass rarely increases, even upon ingestion of large meals, we therefore explored possibility rise in mean circulatory filling pressure (MCFP) serves venous during digestion. this end, measured blood flows pressures anaesthetized Python regius The snakes exhibited...

Blood flow in systemic ($$\dot{Q}_{\mathrm{sys}\,}$$) and pulmocutaneous ($$\dot{Q}_{\mathrm{pul}\,}$$) arteries was measured as a function of body temperature (10°, 20°, 30°C) at rest following enforced physical activity conscious, adult cane toads (Bufo marinus). Arterial mixed venous hemoglobin concentration (CHb) total oxygen content (Co2, tot) were separate group under identical conditions. Heart rate (fH) ($$\dot{Q}_{\mathrm{tot}\,}$$) increased significantly ($$P< 0.001$$) with...