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Biomedical subjects

P A Witt

Publications and source records attributed to P A Witt.

7 recordsLinked to original sources
PubMed1991

Norepinephrine and ATP are synergistic in the mouse vas deferens preparation.

Norepinephrine (NE) and ATP are thought to be neurotransmitters involved with contractions of the mouse vas deferens (MVD) in vitro. The EC50 values of exogenously administered NE and ATP were 5.16 +/- 1.37 and 315.32 +/- 221.18 microM, respectively. Contractions of MVD induced by electrical field stimulation were blocked by alpha,beta-methylene adenosine-5'-triphosphate (purinergic desensitizer) and not by prazosin (alpha 1-adrenoceptor antagonist), suggesting that ATP is the predominant transmitter in this preparation. However, because the EC50 value for ATP was over 100-fold greater than that for NE, we performed isobolographic analysis comparing NE and ATP actions separately and together. Our results demonstrated a synergistic interaction of ATP and NE. At all ratios of ATP:NE examined, exogenous NE enhanced contractile responses to ATP. These data indicate that the co-transmitters, NE and ATP, in the MVD interact postjunctionally in a synergistic manner.

Adenosine Triphosphate↗
PubMed1990

Effect of dietary tryptophan on the development of hypertension in the Dahl salt-sensitive rat.

Dahl salt-sensitive rats are inbred on the basis of their tendency to develop hypertension when placed on a high salt diet. The present study investigated the effects of chronic dietary tryptophan (trp) at 50 g/kg food on the development of hypertension in these animals under conditions of both normal and elevated dietary salt. Dietary trp attenuated the development of hypertension in inbred Dahl salt-sensitive (DS/JR) rats and had no effect upon the patterns of development of systolic blood pressures in the normotensive controls, the inbred Dahl salt-resistant (DR/JR) rat and the outbred parental Sprague Dawley (SD) rat. Cardiac hypertrophy, which is associated with Dahl salt-induced hypertension, was blocked by the high trp diet. Further work will be necessary to elucidate the mechanisms by which dietary trp protected against the development of hypertension and cardiac hypertrophy in DS/JR rats.

Animals↗
PubMed1983

Facilitating "flow" through therapeutic recreation services.

The rationale and means for facilitating flow for disabled individuals in situational and community recreation settings is discussed. The flow model and arousal model are discussed and implications of leadership aimed at facilitating flow are delineated. Specific principles discussed are: attracting attention, arranging complexity to provide optimal challenge, narrowing the stimulus field, minimizing extrinsic rewards, arranging for immediate feedback, and minimizing the individual's awareness of and focusing on the outcomes of involvements.

Awareness↗