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Biomedical subjects

C F Meier

Publications and source records attributed to C F Meier.

11 recordsLinked to original sources
PubMed1991

Suppressor effects in the relations of psychological variables to resting blood pressure.

The role of suppressor effects in obscuring the relation of psychological variables and blood pressure was studied. Forty-five nonmedicated patients in a family practice rated themselves relative to their peers on a series of characteristics. Two of these, trapped and lonely, exhibited marked suppressor effects in their relationship with each other and resting blood pressure. Self-ratings of lonely exhibited a moderately strong positive association with ratings of trapped (r = .63) while only ratings of lonely showed a significant correlation with resting systolic blood pressure (r = .31). Yet when the suppressor effects of the ratings on feeling lonely were removed in the regression analyses, the ratings on feeling trapped showed a significant positive association with resting systolic pressure (r = .42). Similarly, while neither ratings on feeling lonely or on feeling trapped showed separately a significant association with resting diastolic pressure, when suppressor effects were removed in the regression analyses, the ratings of trapped were significantly associated with diastolic pressure in a positive direction (r = .34) and ratings of lonely were significantly associated in a negative direction (r = .33). The significance of this specific suppressor effect and the implications of suppression for psychosomatic research are discussed.

Adult↗
PubMed1989

Relationship of expressed anger to forearm muscle vascular resistance.

The relationship of style of anger expression to physiological reactivity was examined in 45 nonmedicated subjects during their performance of three tasks with contrasting response demands. The primary physiological focus was on forearm muscle vascular resistance (FMVR) with forearm muscle blood flow (FMBF), digital pulse volume (DPV), digital vascular resistance (DVR), heart rate (HR), diastolic blood pressure (DBP), systolic blood pressure (SBP), and electrodermal frequency (EF) monitored. Family Expressed Anger, i.e. the overtness of anger expression in the subject's family of origin, was related to FMVR such that the more anger was expressed in the family of origin, the greater the vasoconstriction during Mental Arithmetic and the less the vasoconstriction during Anger Imagery. Self Expressed Anger, i.e. the degree to which others were aware when the subject was feeling angry, was related to SBP and DBP during Vigilance with a lesser degree of anger expression going with greater blood pressure increases. The meaning of these findings in relation to task appraisal and task demand is discussed.

Adult↗
PubMed1988

Abnormal electrical activity induced by free radical generating systems in isolated cardiocytes.

Oxygen free radicals may participate in a variety of pathological cardiac conditions which are associated with an increased incidence of arrhythmias. However, evidence that free radicals per se can alter the electrical function of the myocardium is not convincing. Physiological solutions containing 3 mM dihydroxyfumaric acid (DHF), a compound known to generate free radicals, were superfused over calcium-tolerant cells isolated from the adult canine ventricle. The time course for changes in transmembrane action potentials was monitored using conventional microelectrode techniques. Changes were observed which could be conveniently segregated into three stages. Initially during superfusion with DHF, the voltage of the action potential plateau became more positive and the action potential duration increased (stage 1). Continued superfusion was associated with the development of both early and delayed afterdepolarizations (stage 2), which occasionally produced triggered beats. Subsequently, some cells failed to repolarize beyond -40 mV following an action potential upstroke. In cells which maintained normal levels of resting membrane potential, early and delayed afterdepolarizations ceased concomitant with the development of an increasingly more negative plateau voltage. Action potential duration decreased and plateau potential "collapsed", eventually merging with the resting level of the membrane potential. Resting membrane potential then gradually depolarized to less than -40 mV and all cells became inexcitable within 6 to 20 min (stages 3). Exposure of cells to xanthine (2 mM): xanthine oxidase (0.01 U/ml), another system known to generate free radicals, produced similar results. Superfusion with DHF solutions containing either superoxide dismutase or catalase delayed the appearance and attenuated the development of the changes in the cardiocyte action potential. The results demonstrate that isolated cardiocytes exposed to free radical generating solutions can undergo changes in their electrophysiological activity that resemble those said to underlie disturbances of cardiac rate and rhythm in the clinical setting.

Action Potentials↗
PubMed1986

Effect of yohimbine on action potentials recorded from isolated canine ventricular myocytes.

Yohimbine is used extensively as an alpha 2-adrenoceptor antagonist. This drug also inhibits sodium channels in the squid axon. In this study we investigated the electrophysiological effects of yohimbine in isolated canine ventricular myocytes. Yohimbine produced a reversible and concentration-dependent decrease in the maximum upstroke velocity and a slight increase in the action potential duration. The maximum upstroke velocity was reduced by over 90% by 10(-4) M yohimbine. It did not effect the resting or plateau potentials in control or isoproterenol-treated cells. Delayed after-depolarizations were also inhibited. These data suggest that yohimbine can produce a local anesthetic effect which is primarily due to inhibition of sodium channels.

Action Potentials↗
PubMed1986

Electrophysiological properties of cultured adult rat ventricular cardiac muscle cells.

Action and resting potential characteristics of isolated adult rat myocardial cells maintained in culture for 10-28 days are described. Resting potentials averaged -76.3 +/- 2 mV in 5 mM extracellular [K+] ([K+]o). Resting potentials changed by 54.3 mV/decade change in [K+]o for concentrations greater than 5 mM. The average maximum rate of rise of action potential (Vmax) was 117.7 +/- 10 V/s with overshoots of 34.6 +/- 2.5 mV. Action potential durations (APD) to 0 and -40 mV and full repolarization were 21.8 +/- 3.9, 36.3 +/- 6.0, and 206 +/- 16.9 ms respectively. Action potential configurations were qualitatively similar to those previously reported by others for rat myocardial tissue or freshly dissociated cells. Tetrodotoxin (4 micrograms/ml) decreased Vmax to less than 24 V/s and decreased overshoot and APD. Isoproterenol (10(-8) M) decreased APD with slight elevation of the overshoot. Verapamil (10(-5) to 10(-4) M) depressed overshoot and plateau while slowing the final phase of repolarization. Verapamil (10(-4) M) depressed upstroke velocity and blocked excitability. While APDs recorded from these cultured cells are apparently longer than those reported by others for rat myocardial APDs, the values of all other electrophysiological parameters recorded are within the limits previously reported for normal rat myocardial tissue. These data indicate that adult rat myocardial cells maintained in tissue culture for 10-28 days possess electrophysiological properties and responses to pharmacological agents similar to adult rat myocardial tissue or undamaged freshly isolated cells.

Action Potentials↗
PubMed1985

The paradoxical relation between diastolic blood pressure change under stress and the H factor of the Jenkins Activity Survey.

This study examined the relation of the Type A scale and of the three factors of the Jenkins Activity Survey to the cardiovascular responses of twenty-six subjects during two stressful tasks. The two tasks were reaction time (RT) and paced arithmetic (PA) and the sample was drawn from a general medical practice. While heart rate correlated directly with the subject's score on the Hard Driving and Competitive Factor (H), diastolic blood pressure response to PA was inversely related to the subject's Type A and factor H scores. This paradoxical inverse relation remained highly significant when the diastolic pressure in the rest preceding PA was statistically controlled.

Adult↗
PubMed1981

Cesium blockade of delayed outward currents and electrically induced pacemaker activity in mammalian ventricular myocardium.

The effects of Cs+, 5-25 mM, were studied in cat and guinea pig papillary muscles using voltage clamp and current clamp techniques. In solutions containing normal K+, the major effects of Cs+ were depolarization of the resting potential and reduction of the delayed outward current (ixl) between -80 and -20 mV. Both inward and outward portions of the isochronal current voltage relation (l-s clamps) were reduced by extracellular Cs+. This resulted in a substantial reduction of inward rectification and, by subtraction from the normal I-V relationship, the definition of a Cs+-sensitive component of current. Under current clamp conditions, 5-10 mM Cs+ produced a dose-dependent slowing of repetitive firing induced by depolarization. At higher concentrations (25 mM) the resting potential was depolarized and repetitive activity could not be induced by further depolarization. However, release of hyperpolarizing pulses was followed by prolonged bursts of repetitive action potentials, suggesting partial reversal of blockade or participation of another pacemaker process. The experimental results and a numerical simulation show that under readily attainable conditions, reduction in an outward pacemaker current may slow pacemaker activity.

Action Potentials↗
PubMedDate not supplied

Relationship of resting blood pressure and heart rate to experienced anger and expressed anger.

Forty-five nonmedicated subjects rated on analog scales the anger they experienced at home and at work (Experienced Anger). They also rated the extent to which others were aware of their anger (Expressed Anger) and the extent to which anger had been expressed in their families or origin (Family Expressed Anger). They were then physiologically monitored during a 2-min relaxation period that followed habituation to the laboratory setting. For the group as a whole, Expressed Anger was inversely related to systolic (SBP) and diastolic (DBP) blood pressure while Family Expressed Anger was inversely related to SBP only. When the sample was divided into normotensive and hypertensive subgroups, the normotensives showed significant associations between Experienced Anger and SBP, Expressed Anger and DBP, and Family Expressed Anger and SBP. The hypertensive subgroup showed no significant associations. Both males and females showed a significant association between Expressed Anger and DBP, but only females showed this relationship with SBP. It is concluded that coping with anger by conscious inhibition of its expression is associated with increases in both systolic and diastolic blood pressure.

Adaptation, Psychological↗