Myung K. Park

Direct Blood Pressure Measurements in Brachial and Femoral Arteries in Children

Intra-arterial pressure in the brachial artery was compared with that in the femoral artery in children. There were no significant differences in systolic, diastolic, or mean pressures. The average auscultatory systolic pressure in the arm, obtained with a cuff 20% wider than the limb, was identical to the average direct systolic pressure in the brachial and femoral arteries. The auscultatory systolic pressure in the leg, using the same criterion for cuff width, was 11 mm Hg higher than the direct pressures. The discrepancy could represent (1) a systematic error in cuff size of inadequate width or length or (2) additional systolic amplification between the femoral and popliteal arteries. Since the femoral pressure is widely used in cardiac catheterization, this pressure is suggested as the standard for calibrating auscultatory technics. For leg blood pressure measurements a cuff at least 25% wider than the average leg diameter and long enough to encircle the limb is recommended.

Prostaglandin E2 and its antagonists: Effects on autonomic transmission in the isolated sino-atrial node*

Abstract Prostaglandin E2 (PGE2) and its antagonists were tested for their effects on the chronotropic responses induced by electrical stimulation of autonomic nerve fibers in the isolated, spontaneously beating, rabbit sino-atrial node. PGE2 (8 × 10−7M) almost completely blocked positive chronotropic responses induced by stimulation of intrandal sympathetic fibers at low frequencies (2 – 5 Hz), while it had no effect at high frequencies of stimulation (20 – 100 Hz). Negative chronotropic responses induced by stimulation of intranodal parasympathetic fibers were only slightly and insignificantly reduced by PGE2 at low frequencies (2 – 20 Hz), and were increased at high frequencies (50 – 100 Hz). Three prostaglandin antagonists, polyphloretin phosphate (PPP), 7-oxa-13-prostynoic acid (EC-I-148) and 1-acetyl-2-(8-chloro-10,11-dihydrodibenz(b,f)(1,4)oxazepine-10-carbonyl) hydrazine (SC-19220), failed to antagonize the inhibitory effects of PGE2 on the chronotropic response induced by stimulation of intranodal fibers in the isolated sino-atrial node.

Effect of polyphloretin phosphate and 7-oxa-13-prostynoic acid on the vasoactive actions of prostaglandin E2 and 5-hydroxytryptamine on isolated human umbilical arteries

Abstract Two prostaglandin antagonists, polyphloretin phosphate (PPP) and 7-oxa-13-prostynoic acid (EC-I-148) were examined for their ability and selectivity to block the vasoactive actions of prostaglandin E 2 and 5-hydroxytryptamine on isolated human umbilical arteries. Polyphloretin phosphate was found to be a weak antagonist of prostaglandin E 2 and exhibited a low degree of selectivity since responses to 5-hydroxytryptamine were also blocked. EC-I-148 (3.25 × 10 −5 M ) demonstrated a strong and selective antagonism to the contractions produced by prostaglandin E 2 because contractions to 5-hydroxytryptamine were not altered. EC-I-148 contracted umbilical artery strips in concentrations which antagonized responses to PGE 2 .

Accurate Blood Pressure Measurement in Children

Accurate blood pressure determination is crucial in the management of critically ill infants and children, in detecting secondary hypertension amenable to surgical correction, and in the early detection of essential hypertension. However, the pediatric literature consists of contradictory methodology and extreme variations in the «limits of normal». An indirect blood pressure measuring device requires validation against a direct arterial pressure

GLYCOSIDE AND AGLYCONE INOTROPISM: INFLUENCE OF TEMPERATURE ON THE RATE OF ONSET

Abstract The onset of inotropism of a cardiac glycoside (strophanthin) and an aglycone (acetylstrophanthidin) was examined at three different temperatures (27, 32 and 37° C) in isolated rabbit left atria driven at a beat interval of 10 sec. The rate of onset of glycoside inotropism was highly dependent on temperature (the higher the temperature the faster the onset), while that of the aglycone was not. It is suggested that cardiac glycosides and aglycones may gain access to the “digitalis inotropic receptor” via different processes: glycosides via a highly temperature-dependent, and presumably active, process and aglycones via a temperature-insensitive, and presumably passive, process.