Preoperative shift from glibenclamide to insulin is cardioprotective in diabetic patients undergoing coronary artery bypass surgery.

AIM: The cardioprotective effects afforded by volatile anesthetics, i.e. isoflurane, during heart surgery may be due to preconditioning of the myocardium through the activation of KATP channels. The aims of this study were to establish whether glibenclamide prevents the isoflurane-induced cardioprotection in diabetic patients undergoing coronary surgery (CABG) and whether this cardioprotective effect can be restored by preoperative shift from glibenclamide to insulin therapy. METHODS: We enrolled 60 patients undergoing CABG. Twenty consecutive non-diabetic patients were randomized to receive conventional anesthesia (CA) or conventional anesthesia plus isoflurane (ISO) (added to the inspired oxygen before starting cardiopulmonary bypass); 40 consecutive diabetic patients in chronic treatment with oral glibenclamide were randomized to conventional anesthesia (G-CA), conventional anesthesia plus isoflurane (G-ISO), conventional anesthesia after shifting to insulin (I-CA) or conventional anesthesia plus isoflurane after shifting to insulin (I-ISO). Serum levels of cardiac troponin I (CTnI) and CK-MB, as markers of ischemic injury, were obtained 1, 24, 48 and 96 hours, postoperatively. RESULTS: Postoperative peak levels of CTnI and CK-MB were lower in ISO than in CA (0.5+/-0.3 vs 2.8+/-2.2 ng/ml, p<0.05 and 61+/-27 vs 79+/-28 U/L, p<0.05, respectively), as well as in I-CA and I-ISO than G-CA and G-ISO groups (0.5+/-0.7 and 0.7+/-0.9 vs 3.5+/-3 and 2.7+/-2.5 ng/ml, p<0.05; 47+/-7 and 41+/-5 vs 85+/-28 and 50+/-23 U/L, p<0.05, respectively). No significant differences were detected in postoperative hemodynamic variables or in-hospital outcome. CONCLUSION: This prospective randomized study shows a cardioprotective effect of preoperative administration of isoflurane during CABG. Such an effect is prevented by glibenclamide, but can be restored in diabetic patients by preoperative shift from glibenclamide to insulin.

A new aortic Dacron conduit for surgical treatment of aortic root pathology.

BACKGROUND: This article describes a new aortic Dacron conduit that has been designed for use in all types of surgery of the aortic root. Its use is aimed at facilitating the surgical procedure and obtaining a natural anatomical configuration of the aortic root. METHODS: The modified Dacron conduit is obtained by adding a smaller piece of Dacron tube that is resilient in the horizontal plane to one end of a standard Dacron conduit. Upon implantation, this small piece of Dacron conduit will stretch in the horizontal plane creating pseudosinuses and a new sinotubular junction. This modified conduit has been used in 4 cases for a Bentall operation in association with a mechanical or a biological valve, in 4 cases in a Yacoub type of valve sparing procedure and in 1 case in a David type I of valve sparing procedure. All patients had aortic root aneurysm with severe aortic regurgitation. There were 6 males and 3 females with a mean age of 61 +/- 16 years. In most cases a 28 mm Dacron conduit was used. RESULTS: All surgery was carried out without mortality or morbidity. The creation of pseudosinuses was confirmed intraoperatively by visual inspection. Transesophageal echocardiography in patients who had undergone the Bentall operation showed a normally functioning valve prosthesis with a suitably shaped aortic root. In patients who had undergone the valve sparing procedures it showed a competent aortic valve, the creation of pseudosinuses of normal shape and depth, and the presence of a well defined sinotubular junction. Angiography confirmed that the prosthetic aortic root perfectly resembled the normal root anatomy. CONCLUSIONS: This modified new aortic root conduit appears to perfectly reproduce a normal root anatomy without the need of modifying the original techniques.

Characterization of the adrenergic activity of carbuterol (SK&F 40383-A).

Carbuterol is a beta-adrenergic bronchodilator with selectivity for bronchial smooth muscle relative to cardiac and vascular tissues of several species including man. The present studies were undertaken to further characterize its adrenergic profile. In vitro studies demonstrated that carbuterol was a direct acting beta-adrenergic agonist, not dependent on endogenous catecholamine release, and was devoid of alpha-adrenergic agonist activity. The activity of the racemate was shown to reside primarily in the l-enantiomer. Carbuterol inhibited immunologically induced release of histamine and slow reacting substance of anaphylaxis from passively sensitized fragmented rhesus monkey lung and also inhibited passive cutaneous anaphylaxis in rats. The relatively weak stimulant activity of carbuterol on beta1 receptors mediating both rate and force of contraction was confirmed in anesthetized open-chest dogs. In the anesthetized cat, carbuterol was significantly less potent than isoproterenol in decreasing diastolic blood pressure, increasing heart rate, and decreasing the tension and degree of fusion of incomplete tetanic contraction of the soleus muscle.

Adrenergic agents. 6. Synthesis and potential beta-adrenergic agonist activity of some meta-substituted p-hydroxyphenylethanolamines related to salbutamol.

Salbutamol, an adrenergic receptor agonist with selectivity for tracheobronchial vs. cardiac muscle, differs from the catecholamine N-tert-butylnorepinephrine in that it bears a hydroxymethyl, rather than a phenolic, group in the meta position. In a search for new bronchodilating agents with minimal cardiovascular side effects, a series of derivatives, in which this m-hydroxymethyl group is modified, was prepared. These compounds were examined for potential bronchodilator activity in an in vitro test that measures relaxation of guinea pig tracheal smooth muscle. Potential cardiac stimulant activity was evaluated in vitro by monitoring changes in the rate of contraction of spontaneously beating guinea pig right atria. Although many of these compounds retained a high degree of potency, all were less effective than salbutamol in the tracheal test. Several of the derivatives, notably ones bearing 1-hydroxyethyl (1d), 1,2-dihydroxyethyl (1f), 1-hydroxy-2-methoxyethyl (1g), and 2-hydroxy-1-methoxyethyl (1h) substituents in place of the parent's m-hydroxymethyl group, however, were considerably more selective for tracheobronchial vs. cardiac muscle in the in vitro tests utilizing guinea pig tracheal and right atrial muscle.

Adrenergic agents. 4. Substituted phenoxypropanolamine derivatives as potential beta-adrenergic agonists.

A series of 1-(substituted phenoxy)-3-(tert-butylamino)-2-propanols in which the ring substituents were 3,4-dihydroxy (6f), 3- and 4-hydroxy (6g and 6h, respectively), 3-hydroxy-4-methylsulfonamido (6i), its 3,4-transposed isomer (6j), and 4-methylsulfonylmethyl (6k) was prepared and examined for beta-adrenergic agonist and/or antagonist properties. Two of these compounds, 6f and 6j, were potent beta-adrenoreceptor agonists in in vitro tests that measure a compound's ability to relax guinea pig tracheal smooth muscle and to increase the rate of contraction of guinea pig right atria. Several compounds had a dose-dependent effect. Although they produced potent beta-adrenergic agonist activity at low concentrations, 6g, 6h, and 6j antagonized the effects of a standard beta-adrenoreceptor agonist at higher concentrations. The methylsulfonylmethyl derivative 6k produced beta-adrenergic blocking effects as demonstrated by attenuation of isoproterenol-induced increases in the rate of contraction of an isolated rabbit heart preparation. On the basis of these pharmacological results, coupled with NMR spectral data, it appears that the previous suggestion that aryloxypropanolamines interact with beta-adrenocreceptors as a consequence of their ability to assume an orientation in which the benzene ring the ethanolamine moieties can be superimposed on those of corresponding adrenergic phenylethanolamines is invalid. An alternative "bicyclic" rigid conformation involving two intramolecular hydrogen bonds in the protonated form of the aryloxypropanolamines is suggested to account for the similar beta-adrenoreceptor activity of these compounds and related phenylethanolamines.

Adrenergic agents. 3. Synthesis and adrenergic activity of some catecholamine analogs bearing a substituted sulfonyl or sulfonylalkyl group in the meta position.

The m-phenolic group of catecholamine beta-adrenergic agonists may be replaced by various functionalities capable of undergoing H bonding. Considerable latitude in the nature of the OH simulating group is permissible with retention of activity; however, the most extensively studied analogs are ones in which a mobile proton is attached to an O or N atom. In a search for new selective bronchodilators a series of catecholamine analogs bearing a substituted sulfonyl or sulfonylalkyl group in the meta position (i.e., groups in which the mobile H is attached to a C atom) was examined. These compounds were studied for beta-adrenergic agonist activity in vitro by measuring their ability to relax tracheal smooth muscle and to increase the rate of spontaneously beating right atria of guinea pigs. Adrenergic activity was influenced by the nature of the alkylene bridge between the sulfonyl and aromatic groups, branching of the ethanolamine side chain, stereochemistry, and substitution of the sulfonyl and amino groups. Beta-adrenergic blockage was noted for some compounds having the sulfonyl attached directly to the ring. Greatest beta-adrenergic agonist potency and tissue selectivity was observed with a m-MeSO2CH2 substituent. One of these compounds, alpha-[[(1,1-dimethylethyl)amino]methyl]-4-hydroxy-3-[(methylsulfonyl)methyl]benzenemethanol hydrochloride (sulfonterol hydrochloride, USAN), was studied more extensively in animals and is presently being examined for bronchodilator activity in man.