摘要:

Simultaneous recording of membrane potentials and contractility in isolated rat atria by means of intracellular micro-electrodes and a sensitive strain gage has been used to establish the normal characteristics of the tissue as well as effects of temperature, stimulus frequency and initial tension on muscle. Preliminary correlations between duration of the action potential and the degree of contraction indicate that the rate of repolarization is of major importance in determination of the contractile response.

ISSN:0009-7330    

出版商:OVID    

年代:1955

数据来源: OVID

摘要:

A hydraulic model was designed to study the effects of converging streams such as occur in patent ductus arteriosus. The results showed that flow across the fistula was dependent primarily on the resistance at the outlets of the “systemic” as against the “pulmonic” circulation. Even very slight differences in resistance could effect very large shunts. When the left ventricular output was great, the loss across the shunt was relatively unimportant. However, when the left ventricular output was low, most of its flow passed across the shunt and the systemic delivery virtually ceased. This situation became much more severe if the systemic resistance was raised even slightly above that of the pulmonic outflow path.

ISSN:0009-7330    

出版商:OVID    

年代:1955

数据来源: OVID

摘要:

Responsiveness of the arterial vessels to intravenous and topically applied epinephrine was determined before and after denervation. Responsiveness to injected epinephrine increased 14 days after denervation; responsiveness to topically applied epinephrine was unaffected by denervation; arterial vessels remained dilated in excess of three weeks following denervation.

ISSN:0009-7330    

出版商:OVID    

年代:1955

数据来源: OVID

摘要:

Central (aortic or subclavian), brachial, radial and femoral pressure pulses were recorded simultaneously in 12 healthy subjects during conditions of rest, exercise and 70 degree head-up tilt. Peripheral systolic pressure at rest uniformly exceeded the central systolic pressure generated by the same heartbeat. The average radial pulse pressure was 146, 146 and 165 per cent of central pulse pressure during rest, exercise and tilt while radial mean pressures were 94, 93 and 98 per cent of central mean pressures respectively. Summation of the incident pulse wave with reflected waves from the periphery and resonance effects in the peripheral arterial systems may produce these changes in pressure and contour.

ISSN:0009-7330    

出版商:OVID    

年代:1955

数据来源: OVID

摘要:

Experiments show that the right ventricle is weakened to the point of irreversible failure by decreased coronary artery pressure and also demonstrate that augmented coronary artery pressure can cause a remarkable increment of the right ventricular strength. Both ventricles, even when in otherwise irreversible decompensation, can be restored to full functional competence by various maneuvers which augment coronary blood flow. The studies reported appear to have important clinical applications in the treatment of circulatory disturbances of the right ventricle.

ISSN:0009-7330    

出版商:OVID    

年代:1955

数据来源: OVID

摘要:

Changes in length and circumference of the left ventricle were recorded simultaneously by variable resistance gages on its external surface in intact dogs. The absolute changes in circumference were considerably greater than the changes in length, but the relative changes in these dimensions were similar (averaging around 2 to 3 per cent). Under most circumstances, the length and circumference vary in the same direction but occasionally inexplicable differences in response were observed.

ISSN:0009-7330    

出版商:OVID    

年代:1955

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1955

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1955

数据来源: OVID