Norepinephrine (NE) released from the sympathetic nerve endings is the main neurotransmitter controlling melatonin synthesis in the mammalian pineal gland. Although neuropeptide Y (NPY) co-exists with NE in the pineal sympathetic nerve fibers it also occurs in a population of non-adrenergic nerve fibers located in this gland. The role of NPY in pineal physiology is still enigmatic. The present ...

Isolated tissue preparations are commonly used to study the effects of drugs on specific type of receptors. These preparations are also used for bioassay of drugs, characterisation of specific receptor or its subtypes, to determine concentration response curve of an agonist, to study antagonism of drug and in new drug discovery.[1] Isolated heart and rectus abdominis of frog are the two commonl...

Zataria multiflora Boiss. is used in Iranian traditional medicine to treat gastrointestinal disorders and menrrhalgia. The inhibitory effect of this herb on rat ileum contractions is also reported. The aim of this study was to investigate the effect of Zataria multiflora Boiss. hydroalcoholic leaf extract (ZHLE) on isolated rat uterus in presence of some known uterus stimulants. Pieces of virgi...

Purpose. To investigate the vasomotive activity upon the external ophthalmic artery of vasointestinal peptide (VIP) and neuropeptide Y (NPY) using a previously developed model. Methods. Isolated rabbit eyes (n = 12) were perfused in situ with tyrode through the external ophthalmic artery. Effects of intra-arterial injections of NPY 200 μg/ml (Group A; n = 6) and VIP 200 μg/ml (Group B; n = 6) o...

We find that St. Louis encephalitis virus cultured in 10 per cent serum-Tyrode solution plus brain tissue from 1-day-old innately susceptible mice attains a higher titre than when cultured in a similar solution plus brain tissue from 1-day-old closely related, yet innately resistant mice. This difference in titre persists regardless of whether the serum comes from innately susceptible or resist...

Movement characteristics of freely swimming spermatozoa were studied with high-speed cinemicrography. At 21 degrees C, flagellar beat frequency was higher in midcycle human cervical mucus than in native semen or Tyrode's solution; the beat shape differed, possessing diminished amplitude and wavelength. Although the spermatozoa swam straighter in the mucus, the progressive swimming speeds did no...

Carbachol (10-8-10-3 M) caused a phasic contraction in the guinea-pig taenia caecum suspended in the Ca-free, K-Tyrode solution. The action of carba chol was concentration-related and was completely antagonized by atropine (10-6 g/ml). The capacity to contract in the absence of external Ca was removed by short term exposure to a high concentration of carbachol (...

The effect of aminoglycoside antibiotics upon the electrically induced release of endogenous opioid peptides from the guinea-pig ileum was studied in vitro. Stimulation of guinea pig ileum at 10 Hz in normal Tyrode solution resulted in the naloxone sensitive depression of the twitch contractions of this muscle. Addition of aminoglycosides during 10 Hz stimulation diminished this naloxone sensit...

Mechanoelectric transduction can initiate cardiac arrhythmias. To examine the origins of this effect at the cellular level, we made whole cell voltage-clamp recordings from acutely isolated rat ventricular myocytes under controlled strain. Longitudinal stretch elicited noninactivating inward cationic currents that increased the action potential duration. These stretch-activated currents could b...

1. Cultures of typhus fever rickettsiae were as a rule found to remain viable and virulent after being stored at 37 degrees and -20 degrees C. for several months, whereas they failed to survive when stored at the intermediate temperatures of 20 degrees and -4 degrees C. for 4 weeks and 10 days respectively. In one instance cultures were stored at 37 degrees C. for 8 months without having been t...