Blood gases and cardiovascular shunt in the South American lungfish (Lepidosiren paradoxa) during normoxia and hyperoxia

The South American lungfish (Lepidosiren paradoxa) has an arterial P(O2), (Pa(O2)) as high as 70-100 mm Hg, corresponding to Hb-O(2) saturations from 90% to 95%, which indicates a moderate cardiovascular right to left (R-L) shunt. In hyperoxia (50% O(2)), we studied animals in: (1) aerated water combined with aerial hyperoxia, which increased Pa(O2) from 78 +/- 2 to 114 +/- 3 mm Hg and (2) and aquatic hyperoxia (50% O(2)) combined room air, which gradually increased Pa(O2) from 75 +/- 4 mm Hg to as much as 146 +/- 10 mm Hg. Further, the hyperoxia (50%) depressed pulmonary ventilation from 58 +/- 13 to 5.5 +/- 3.0 mLBTPS kg h(-1), and Pa(CO2) increased from 20 +/- 2 to 31 +/- 4 mm Hg, while pHa became reduced from 7.56 +/- 0.03 to 7.31 +/- 0.09. At the same time, venous P(O2) (Pv(O2)) rose from 40.0 +/- 2.3 to 46.4 +/- 1.2 mm Hg and, concomitantly, Pvco, increased from 23.2 +/- 1.1 to 32.2 +/- 0.5 mm Hg. R-L shunts were estimated to about 19%, which is moderate when compared to most amphibians. (C) 2010 Elsevier B.V. All rights reserved.

The influence of age on blood pressure evaluation of hypertensive subjects

The aim of this study was to determine whether age influences the concordance between different methods of blood pressure (BP) measurement and ambulatory BP monitoring (ABPM) in hypertensive subjects. We studied two groups: I, individuals younger than 50 years (n = 57), and II, individuals aged 60 years or older (n = 55). They were submitted to the performance of one ABPM, office BP measurements, home BP monitoring (HBPM), and BP measurements at a public health center (PHCBP). Student`s t-test, Fisher`s test and Lin coefficient were calculated. For Group II, systolic and diastolic pressures measured by HBPM were higher than by day ABPM (p < 0.01). The concordance between day ABPM and the other methods was lower for Group II than for Group I. There was a good concordance between systolic day ABPM and office BP, and between systolic ABPM and PHCBP only for Group I (Lin coefficient = 0.71 and 0.73). Group II reported better sleep quality after ABPM (p < 0.05). Considering 24-h ABPM, 52.6% of Group I and 29% of Group II were controlled (p < 0.01). Concluding, there was worse concordance between different methods of BP measurements and day ABPM in the older group, which had lower hypertension control rate and better tolerance of ABPM. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

Stereological and allometric studies on neurons and axo-dendritic synapses in the superior cervical ganglia of rats, capybaras and horses

The superior cervical ganglion (SCG) in mammals varies in structure according to developmental age, body size, gender, lateral asymmetry, the size and nuclear content of neurons and the complexity and synaptic coverage of their dendritic trees. In small and medium-sized mammals, neuron number and size increase from birth to adulthood and, in phylogenetic studies, vary with body size. However, recent studies on larger animals suggest that body weight does not, in general, accurately predict neuron number. We have applied design-based stereological tools at the light-microscopic level to assess the volumetric composition of ganglia and to estimate the numbers and sizes of neurons in SCGs from rats, capybaras and horses. Using transmission electron microscopy, we have obtained design-based estimates of the surface coverage of dendrites by postsynaptic apposition zones and model-based estimates of the numbers and sizes of synaptophysin-labelled axo-dendritic synaptic disks. Linear regression analysis of log-transformed data has been undertaken in order to establish the nature of the relationships between numbers and SCG volume (V(scg)). For SCGs (five per species), the allometric relationship for neuron number (N) is N=35,067xV (scg) (0.781) and that for synapses is N=20,095,000xV (scg) (1.328) , the former being a good predictor and the latter a poor predictor of synapse number. Our findings thus reveal the nature of SCG growth in terms of its main ingredients (neurons, neuropil, blood vessels) and show that larger mammals have SCG neurons exhibiting more complex arborizations and greater numbers of axo-dendritic synapses.