ABSTRACT
It already has been known that various ions were participated in phototransduction mechanism of the vertebrate photoreceptor during the visual adaptation. The vitreous humor(VH)contains certain amount of Na+, K+ and Ca++ as well. However, the roles of these ions are unknown except functioning of metabolic process. Our preliminary electroretinogram(ERG) experiments suggested that the permeability of these ions has light dependent activity during the light illumination. We have supported this suggestion more tangibly by trying out various experiments with bullfrog eyes as a reference of visual adaptation. The results are summarized as follows: 1)According to our atomic absorption spectroscopic measurements, the concentration of Na+, K+ and Ca++ in light adapted VH was higher than that of dark adapted VH. This result indicated that the light-dependention transport systems which affect the ionic movements might be in internal limiting membrane(ILM). 2)The amplitude of ERG b-wave was reduced by concentration decrement of Na+ and concentration increment of K+ respectively. On the other hand, the elimination of Ca++ within ringer solution resulted in b-wave amplitude increment. 3)Treatment of Na+ hannel blockers(TTX, STX)and K+ channel blockers(Ba++, Cd++, Cs+, 4-AP and TEA)in the vitreous humor side induced the increment and the decrement of b-wave response respectively. Taken together, these results suggest that the light dependent Na+ K+ channels exist in the ILM of vertebrate retina which participates visual adaptation.
Subject(s)
Absorption , Hand , Ions , Light Signal Transduction , Lighting , Membranes , Metabolism , Permeability , Photoreceptor Cells, Vertebrate , Rana catesbeiana , Retina , Vertebrates , Vitreous BodyABSTRACT
BACKGROUND: In order to investigate the effects of intensive training on cardiorespiratory response to maximal exercise in soccer players, graded excercise stress tests were carried out before and after the training, and the results were compared. METHODS: Fourteen male soccer players of a university team with the mean age and career of 19.9 and 7.8 years, respectively, underwent intensive training for approximately 20 weeks, 6 days a week and 4 hours a day, which included running of 2 km daily during the last 8-9 weeks. The symptom-limited maximal exercise test was done by Bruce protocol. RESULTS: After the training. HR max showed no significant changes but Vo2 max, O2 pulse and AT were increased approximately 13%, 12% and 10%, respectively. At maximal exercise, the V(E)/M2 was also increased 18%, but VE/MVV was significantly decreased owing to a marked increase in MVV. However, the rest of various ventilatory parameters showed no significant changes. CONCLUSION: These data indicate that the intensive training of about 20 weeks duration can further improve the level of cardiorespiratory fitness in the soccer players who have been regularly trained and are already highly fit.
Subject(s)
Humans , Male , Exercise Test , Running , SoccerABSTRACT
BACKGROUND: We attempted to study functional and structural changes in the hearts of volleyball players and cardiac effects of a short-term intensive training as disclosed by electrocardiograms(ECG's) and echocardiograms(UCG's). METHODS: In 12 volleyball players of a university team with the mean age and career of 19.9 and 9.2 years, respectively, comparisons of ECG's and UCG's M-mode & Doppler, were made before and after an intensive training of 8 weeks duration. The players have been trained 2-3 hours daily almost year around for many years, and the intensive and comprehensive training given for the current study was 3 hours daily, which included strenuous interval training of 20-30 minutes. The training was divided into two successive sessions. For the first session, the players ran 4km daily as a part of the training for 2 weeks. The second session included repetition of runnging at their maximal speed with short intermissions of stationary running for 6 weekes. RESULTS: The major findings in ECG's were sinus bradycardia(25.0%) and high voltage(33.3%), and those in M-mode UCG's were left ventricular(LV) hypertrophy, LV dilatation or left atrial dilatation being seen in all cases, alone or in combinations. After the training however, there were no significant changes in the incidences of these abnormal findings in ECG's & UCG's, and also in the mean of various echocardiographic parameters reflecting cardiac functions. The E and A waves in Doppler UCG's also showed no changes. The slight but significant changes after the training were limited to the increases in the mean of the sum of S wave in V1 & R wave in V5, and left atrial dimensions. CONCLUSION: In volleyball players who have been regularly trained for many years, the major findings in ECG's were sinus bradycardia and high voltage. Those in UCG's were LV hypertrophy. LV dilatation or left atrial dilation being seen in all cases, alone or in combinations. Nonetheless, after the intensive training of 8 weeks duration, the incidences of these abnormal findings in ECG's and UCG's remained essentially similar, and slight but significant changes were limited to the increases in the sum of S wave in V1 & R wave in V5, and left atrial internal dimensions. These facts suggest that in the regularly trained volleyball players, a short-term intensive training induces only limited cardiac changes as disclosed by ECG's and UCG's.