Effects of dihydroergotamine methanesulfonate on the microcirculation of the rat cremaster muscle.

Effects of dihydroergotamine on the microcirculation of the rat cremaster muscle were investigated microscopically using colour photographic technique. 1. Dihydroergotamine 10(-4) g/ml constricted arterioles of the rat cremaster. 2. Dihydroergotamine 10(-4) g/ml produced a significant contraction of venules. 3. Dihydroergotamine 10(-4) g/ml markedly inhibited the contractile response of noradrenaline 10(-6) g/ml on arterioles of the rat cremaster. The results suggest that dihydroergotamine has an appreciable vasoconstrictive action, especially upon venules, and that dihydroergotamine also has an adrenergic alpha-receptor blocking action. By means of highly sensitive negative colour film we obtained a satisfactory photograph of the rat cremaster's circulation.

Comparison of lactate pyruvate and potassium concentration in the cardiac lymph and, arterial and coronary sinus plasma in dogs.

Lactate (LA), pyruvate (PYR) and potassium (K) concentration in the cardiac lymph were compared with those in the arterial and coronary sinus plasma in dogs. In each substance, there was a good correlation between the plasma and cardiac lymph level in the control period. In respect to LA and PYR, the concentration in the cardiac lymph correlated more with that in the arterial plasma than in the coronary sinus one. During the infusion of isoproterenol, LA and PYR in the plasma increased, while K decreased. Each substance in the cardiac lymph changed to the same degree as in the plasma in mean values. Good correlation was also observed between the arterial plasma and cardiac lymph level during the administration of the agent. However, there was no correlation of PYR between the coronary sinus plasma and the cardiac lymph. During the administration of dipyridamole LA in the coronary sinus plasma increased and that in the arterial plasma decreased. LA in the cardiac lymph did decrease as in the arterial plasma. It is concluded that the concentrations of LA, PYR and K in the cardiac lymph can be changed depending upon changes in those in the plasma and the former two parameters seem to change depending upon those in the arterial plasma rather than the coronary sinus one.

Effects of alpha-D-glucosylglycerol on the in vitro digestion of disaccharides by rat intestinal enzymes.

Alpha-D-glucosylglycerol (GG) is a mixture of 2-O-alpha-D-glucosylglycerol (GG-II), (2R)-1-O-alpha-D-glucosylglycerol (R-GG-I) and (2S)-1-O-alpha-D-glucosylglycerol (S-GG-I). GG has been found to be slightly hydrolyzed in vitro only by rat intestinal enzymes, but hardly at all by other digestive juices. GG suppressed the hydrolysis of maltose, sucrose and isomaltose by rat intestinal enzymes because the amount of glucose in the digestion of a mixture of GG and disaccharide was less than the sum of that in each individual digestion. The consumption of GG was suppressed by isomaltose, but promoted by maltose, with the hydrolysis of GG being suppressed. Sucrose appeared to suppress only the consumption of S-GG-I, suggesting that S-GG-I was hydrolyzed by the active site of sucrase in a sucrase-isomaltase complex. Transglucosylation seems to have occurred more frequently in the individual digestion of maltose and isomaltose than in that of GG and sucrose. GG seemed to promote transglucosylation in the presence of maltose, to suppress it with sucrose, and to delay it with isomaltose.

Synthesis of alpha-D-glucosylglycerol by alpha-glucosidase and some of its characteristics.

It has been found that alpha-D-glucosylglycerol (GG) is contained in such traditional Japanese foods brewed by using koji as sake, miso and mirin, and that GG is formed by transglucosylation to glycerol that is produced by yeast with alpha-glucosidase (EC 3.2.1.20) from koji in the sake mash. GG has also been found to consist of three components, 2-O-alpha-D-glucosylglycerol (GG-II), (2R)-1-O-alpha-D-glucosylglycerol (R-GG-I) and (2S)-1-O-alpha-D-glucosylglycerol (S-GG-I). GG was synthesized from a mixture of maltose and glycerol by the batch method, using alpha-glucosidase (transglucosidase L-AMANO). alpha-Glucosidase seemed to be so stable that the amount of GG increased about 5-fold compared with that in the first reaction by the daily addition of maltose for 10 d. Syrupy GG obtained was found to have the following characteristics: about 0.55-fold sweetness compared with sucrose, high thermo-stability, low heat-colorability, low Maillard reactivity, low hygroscopicity, high water-holding capacity, non-cariogenicity and low digestibility.

Effects of increased cardiac mechanical performances on flow rates of cardiac lymph in dogs.

Relationship between flow rates of cardiac lymph (LF), and coronary blood flow (CF), coronary perfusion pressure (PP), left ventricular peak systolic pressure (LVSP) and heart rate (HR) was studied in open-chest dogs. Intra-coronary administration of catecholamines (CA) and electrical stimulation of the cardiac sympathetic nerve (ES) increased LF transiently with a concomitant rise in the cardiac mechanical performance, while dipyridamole induced no change in LF in spite of a marked increase in CF. Isoproterenol at does of 0.3 and 3x10(8) g/kg induced an increasein LF to 119 +/- 4 and 167 +/- 20% (mean +/- SE); norepinephrine, 0.3 and 3 X 10(7) g/kg, to 118 +/- r and 141 +/- 13%; ES AT 5 and 20 Hz, to 135 +/- 11 and 167 +/- 10%, respectively. Peak responses of LF correlated with changes in LVSP (R = 0.59, N l1,P less than 0.001), CF Tr = 0.53, n = 51, P less than 0.001), PP (r = 0.49, n = 51, P less than 0.001) but not with changes in HR (r = 0.27, n = 51, 0.05 less than P less than 0.10). Cardiac pacing also showed a poor correlation between the changes in LF and HR under the same LVSP within the changes in HR up to 134% of control value (r = -0.12, n = 17, P GREATER THAN 0.50). It is concluded that LF is independent of changes in HR, and increased LF after CA or ES may be caused mainly by an augmented propulsive force.

Effects of propranolo, itramin tosylate and dipyridamole on myocardial phosphate metabolism in anoxic perfused rat hearts.

Effects of propranolo, itramin tosylate and dipyridamole on coronary flow, cardiac activity and phosphate metabolism were investigated in anoxic perfused rat hearts. During anoxia, heart contractions showed a transient increase followed by gradual declines in amplitude and frequency, while ATP and creatine phosphate (CP) contents strikingly decreased accompanying a pronounced increase in inorganic phosphate (Pi). Propranolol added to the anoxic perfusate attenuated the decrease in CP and increase in Pi, whereas heart contractions wre more markedly depressed than by anoxia alone. Similar effects were also seen in electrically paced anoxic hearts. Itramin decreased ATP contents in non-paced anoxic hearts, but did not in paced ones. Dipyridamole did not produce any significant effect on phosphate metabolism in anoxic myocardium. It was considered that propranolol prevented the anoxia-induced reduction in high-energy phosphates by antagonizing catecholamines released by anoxia and that itramin decreased ATP level by inhibiting ATP generation.

Possible mechanisms involved in the coronary vasodilatory response to dopamine.

Dopamine increased coronary blood flow in the dog heart pretreated with alpha-adrenoceptor blocking agents. The coronary vasodilator response was completely inhibited by indomethacin when pretreated with propranolol in addition to alpha blockade. The coronary vasodilation exerted by sodium nitrite was potentiated by indomethacin and adrenergic blockade. In coronary arterial strips, dopamine produced a contraction which was abolished by phenoxybenzamine. Dopamine elicited a dose-dependent relaxation in coronary arterial strips contracted previously by KC1 after pretreatment with phenoxybenzamine. The relaxation was potentiated by indomethacin; this effect was completely blocked by propranolol. Prostaglandin (PG)E1 produced a relaxing response but reduced the dopamine-induced relaxation. From the results it is suggested that beta-adrenoceptor stimulation and release of PG were involved in the coronary vasodilator response to dopamine. PG released by dopamine may increase coronary blood flow on the one hand and reduce beta-adrenoceptor stimulation by inhibiting adenyl cyclase on the other.