Previous articleNext article No AccessBook ReviewsThe Battle against Heart Disease. P. E. Baldry Vladislav KrutaVladislav Kruta Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmailPrint SectionsMoreDetailsFiguresReferencesCited by Isis Volume 63, Number 3Sep., 1972 Publication of the History of Science Society Article DOIhttps://doi.org/10.1086/350965 Views: 1Total views on this site Copyright 1972 History of Science Society, Inc.PDF download Crossref reports no articles citing this article.

Previous articleNext article No AccessBook ReviewsThe History of Coronary Heart Disease. J. O. Leibowitz Vladislav KrutaVladislav Kruta Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Isis Volume 63, Number 2Jun., 1972 Publication of the History of Science Society Article DOIhttps://doi.org/10.1086/350903 Views: 2Total views on this site Copyright 1972 History of Science Society, Inc.PDF download Crossref reports no articles citing this article.

Previous articleNext article No AccessBook ReviewsCharles Scott Sherrington. A Biography of the Neurophysiologist. Ragnar Granit Vladislav KrutaVladislav Kruta Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Isis Volume 59, Number 4Winter, 1968 Publication of the History of Science Society Article DOIhttps://doi.org/10.1086/350442 Views: 2Total views on this site Copyright 1968 History of Science Society, Inc.PDF download Crossref reports no articles citing this article.

EITccts of rapid changes of temperature of about 10o C on the mechanical response of electrically driven guinea-pig left atria suspended in a special chamber (Fig. 1) in Krebs-Henseleit medium have been studied.A simple step change to a higher temperature causes a typical immediate biphasic reaction of the amplitude followed by a progressive transition to a lower level steady state activity. A similar rapid cooling causes a less marked initial biphasic reaction followed by an ascending staircase to the higher steady state level (Fig. 2).In a quiet preparation cooling causes a slight increase of its resting length, warming a slight shortening, both often preceded by an initial deflection in the opposite direction.A short exposure (2 sec.) to a lower or a higher temperature causes besides the modification of the concomitant contraction a disturbance of the steady state dynamic equilibrium which needs several contraction cycles to be repaired.The staircase-like transitions are in fact a third kind of this form of adjustement of the heart muscle contraction to new conditions (rate of activity, input or output pressure, temperature) and seem to represent a general adaptation pattern specific to the heart muscle.A more detailed analysis of the immediate reaction shows that modifications of amplitude and of peak time appear in the contraction occurring during the rapid change of temperature and become more marked, the more the change precedes the contraction. These two modifications run almost parallel, that of the speed of contraction lags behind them, The rapid variation of amplitude seems to result from the primary variation of the duration of shortening.The 90 % relaxation time modification on cooling precedes those of amplitude and of peak time, but on warming is slightly biphasic and its decrease is delayed.

1. After-contractions (AC), i.e. oscillatory variations of the resting length of atrial myocardium which occur under strong positive inotropic influence following an arrest of rhythmic activity, have been studied on isolated electrically driven guinea-pig left auricles at isotonic conditions. Low temperature (15– 17.5°C) and a relatively high stimulating rate (about 1 p. sec.) were used as inotropic agents.2. The amplitude and wave length of AC was found to depend:a) on the activity prior to the rest period, in which the AC occurred, namely, on the number and frequency of the preceding beats–see Fig. 2;b) on the Ca++ concentration in the medium. The higher the activity and/or Ca++ concentration, the greater the amplitude and the shorter the wave length of the AC.3. Concommitant oscillatory variation in restitution of contractility has been described. The restitution is exactly in phase with AC, but has an opposite direction (cf. Fig. 3). The greater the AC at a given moment, the smaller the triggered contraction. This indicates some competition of both types of mechanical reaction, probably for a common driving factor.4. The relation between the AC – and thus the initial muscle length – and triggered contraction is similar to that of Starling's Law.

SUMMARYThe history of the idea of reflex activity in neurophysiology is outlined and the important place in this history of the Czech physiologist G. Procháska is stressed. Procháska was the first who, in 1784, formulated a consistent modern concept of reflex activity.RÉSUMÉL'histoire du concept activité réflexe en neurophysiologie est rapportée à grands traits et la part importante prise dans cette histoire par le physiologiste tchèque G. Procháska est mise en évidence. Procháska est le premier qui a formulé, dès 1784, un solide concept moderne de l'activité réflexe.

Inotropic action of g-strophanthin (1∶4,000.000), its dependence on stimulation frequency, and changes of two main factors determining the contractile force in relation to activity rate, „restitution” and „potentiation” effects, have been examined in isolated left auricles of guinea pig and rat.

(1960). Allure De La Contractilite ET Frequence Optimale Du Myocarde Auriculaire Chez Quelques Mammiferes. Archives Internationales de Physiologie et de Biochimie: Vol. 68, No. 1, pp. 152-164.

HAVING recently completed an edition of the complete works of J. Purkyně, I am preparing to publish his letters. In this connexion I am seeking especially letters which he wrote to the British physiologist, Martin Barry (1802–55), and also any letters which show Purkyně's relations with the Royal Society. I should be grateful if anybody possessing letters by or concerning Purkyně, or anybody knowing of their whereabouts, would write to me.